Initial EFR 7670 dyno results
 

After 13 years with a BNR Stage IV stock hybrid turbo the EFR series turbos finally interested me enough to give something new a try.

I fabbed up a manifold using an old HKS T04Z manifold as the base. I added two Tial MVR 44mm wastegates since I wanted to be able to run low boost on pump gas.

I went with an EFR 7670 as I wasn't really looking for more power, but rather even better power delivery.

As you can see, the 7670 fit the FC well.
Looks like there is room for the larger EFR turbos using this manifold as the exhaust side and center housing is the same, the EFR 8374 and 9180 just have the next size up compressor cover.

Here is the initial dyno at 26psi boost.

I have the 13psi springs in the wastegate because I want to be able to run low boost on pump gas and then turn up the boost on race gas.

The low boost wastegate springs are probably a contributing factor on the boost fade this set up has. It hits peak boost fast, but then fades down. We turned up the manual boost controller and both peak boost and faded boost rose about the same so we went ahead with the tuning session.

Final dyno (shown) is 26psi peak boost and fading to ~20psi from memory.

The AFRs are still richer than 10:1 from about 4,500 to 7,000rpm- that "sag" in the power could probably be fixed leaning it out, but we ran out of time and tolerance to the noise this evening.

I wasn't able to do a full pull at 28psi as it hit 100% duty cycle around 4,000rpm.

https://www.rx7club.com/attachments/...-7670-rx-7-jpg

This is my old BNR Stage IV stock hybrid on the same dyno at 10psi and 18psi where it maxed out.

https://www.rx7club.com/attachments/...s-bnr-dyno-jpg

Definitely an improvement. That is over 400rwhp on a dynojet!

*Probably* just over 400rwhp on a dynojet. I am hoping to find out this Sunday.

Also I noticed the Dynojet loads the engine correctly for the same spool as on the street. Even playing with Dyno Dynamics ramp rates it doesn't load the engine enough at low rpms. Maybe I need to pay for some training/read up on DD to figure it out.

My old hybrid turbo-
Dynojet = 340rwhp @ 12psi.
Dynapack= 340 @ 12psi, 380 @ 14psi.
DynoDynamics= 295rwhp @ 10psi, 320rwhp @ 16psi, 325rwhp @ 18psi.

Here are my results from the 8374 I did today. This was in shootout mod( so they are dynojet figures)

Ran out of time to try a new set of plugs with a smaller gap, and continue trouble shooting..

Will retry again and fit new boost control actuator( medium canister was past its limits)


Boost response is identical on a dynojet with this car, actually slightly higher HP figures on a dynojet...

I did a 4th gear log last night and the DD settings we have are actually spooling it exactly the same as when driving.

We set it off when we reached full boost on my old turbo. I think it is 85 which is 8.5km/sec?

10psi @ 2,500rpm
19psi @ 3,000rpm
26psi @ 3,300rpm

Luckily, I found when driving it holds 26psi until 6,000rpm and then slowly and evenly fades down to 20psi at redline. So, possibly the Dyno Dynamics is not loading enough at high rpm?

http://imagizer.imageshack.us/v2/xq90/913/JVQdvO.jpg


while the EFR line of turbos are a clean sheet of paper design purpose built for our interests instead of hauling trucks down the road it still comes down to pressure and flow to determine power.

as in a compressor map. note that BW did not plot the 60% efficiency line further than 26 pounds so let's just draw in a line in order to speak apples/apples language. do note, however, flow ends when the RPM line goes vertical. just before that the efficiency goes away as too much heat enters the picture.

the 7670 has a very small compressor wheel.

BW EFR 7670 comp wheel is 5.524 average square inches

Garrett GT3582r is 6.386!

while smaller, the wheel is of a stronger material than the cast aluminum GT35. stronger is very important at higher boost where temps can reach 400 F and pressures are extreme. cast aluminum probably gives up a bit of form and flow V billet.

BW shows the backbone in the billet wheel by running the compressor to 44 PSI or 4 Pressure Ratios absolute where it produces max output.

since it is stronger, a billet wheel needs less center mass so it has delivers longer vanes per diameter, and vanes, not the nose, do the heavy lifting.

the 7670 needs all these advantages as the compressor wheel is only 86.5% the size of the GT35.

while there isn't a single component on the EFR line of turbos that isn't superior to other turbos the weight/design of the turbine wheel probably takes center stage.

if you have ever held a turbine wheel in your hand you know they are very heavy. as in boat anchor. take a look at the RPM plot on the compressor map. the 123.3 number is RPM as in 123,000 RPM! now think about early boost as in spool, as in accelerating a heavy turbine wheel.

the EFR line of turbines are around 50% lighter! while i grant you that the primary opposing force to the turbo is moving the air thru the compressor, rotating mass has to be also important.

BW must have agreed as they no doubt invested a lot of effort in the Titanium Alumide material.

all the design features aside, power still gets back to airflow and the compressor map.

maximum rotary rwhp SAE from the 7670:

at 1.68 pressure ratio (Absolute) or 10 PSI 37 pounds/min or 278 hp

at 2.36 PR/20 PSI 54 pounds 407 hp

at 2.77 PR/26 PSI 58 pounds 437

at 4 PR/44 PSI 64 pounds 482

all derived using an estimated 60% efficiency line.

of course these numbers are maximum and your engine/setup may or may not be able to power the turbo to that particular spot on the map.

it is relatively easy to get early boost. a few years ago my maiden voyage on my GT4094r resulted in 30 PSI before 3000 RPM. i had hooked up the wastegate incorrectly and the valve was closed. generally you get higher EGTs. i see high EGTs from improperly designed turbo manifolds which restrict airflow similar to a small hotside.

the downside to a restricted hotside in addition to higher EGTs is lower flow/boost pressure at higher RPMs.

i grant that most of the early power/boost/flow from the EFR line is due to the more efficient design since the 8374 also produces better midrange and it has a 6.23 turbine area. my 9180 is 7.19 hotside area.

i do believe the BW EFR line remains the only 21st century turbo and expect to see others eventually release similar designs down the road.

howard

I am starting to wonder if we will continue to even sell the 7670. The 8374 delivers amazing response with much better midrange and topend compared to the 7670. I do not see a reason to have any better response by moving down to the 7670. Also lower egts and backpressure of bigger turbine section on 8374 is a big plus as mentioned.

I am starting to wonder if we will continue to even sell the 7670. The 8374 delivers amazing response with much better midrange and topend compared to the 7670.

Well, as you said the shootout mode #s you posted for the EFR 8374 are much more like dynojet #s.

If you pm me the settings you entered for shootout mode we might dyno the EFR 7670 that way sometime for a direct comparison- otherwise the chart you posted in shootout mode is no where near to the chart I posted with correction.

Also lower egts and backpressure of bigger turbine section on 8374 is a big plus as mentioned.

Since the 8374 exhaust housing is the same and just the exhaust wheel is 4mm larger lower EMAP/EGT from larger hotside is likely offset by the 7mm larger compressor wheel the exhaust has to power. More work = higher EMAP/EGT.

On my 7670 set-up, because of the shallow merge angle and how close my wastegate runners are to the motor the EMAP pushes the 13psi WG springs open fairly easy compared to the IWG EFR exhaust housing with medium boost cannister.

I think this has a lot to do with my boost fade. Dual 44mm WGs pushed open wide with exhaust flow/pressure don't maintain the compressor RPM and boost drops.

I did the high priority WG though to prevent boost creep on my 13psi low boost pump gas setting and promote WG flow as WG is open at ~2,700rpm (90hp) on 13psi low boost and then has to flow enough exhaust to maintain just 13psi at 7,000rpm (310hp).

I am trying to balance a 13psi low boost setting for pump gas and a 26psi high boost setting for race gas on the same setup (just change boost controller setting) which is a tough job for any turbo!

Also, I don't think I am anywhere near surge line at low rpm, so the EFR 7670 could use much smaller volume exhaust manifold/housing on the low end to improve spool.

Imagine a stock 3rd gen sequential manifold under a divided manifold/housing so that all exhaust gas enters the turbo wheel through one of the T4 divided exhaust housings at low rpm for faster spool.

The 7670 could do this for more power 1,000rpm to 3,000rpm whereas the 8374 is already near surge at low rpm.

So... in judging the EFR 7670 by my results remember the impediments I have shackled the turbo with to meet the criteria of my set-up.

For comparisons sake

I will add 10% to your torque figures

RPM Yours( +10%) VS 8374 (

2000 105 125
2500 150 170
3000 260 250
4000 375 405
5000 330 425

Obviously there is a big difference in boost pressure, but if one had to choose between the two plots, I would pick the 8374. Again I do want to see apples to apples comparison( no boost fade on your setup).

Keep in mind the medium canister( on the 8374) with a lot of preload is not working correctly at all. I wasn't able to verify visually( at what RPM it started cracking). I was able to go from 3 to 5 turns of preload and gain a good 500rpms worth of boost response too.

We will try again with the turbosmart actuator with a 30psi spring. I bet boost response will be even better.

I do want to see your car on a dynojet, with bigger base springs, and more time spent on the tuning. I have two 7670s that I will be tuning shortly too..

Do you have a dynosheet of torque vs boost pressure like the one I posted?

Also when you checked on the street was it 4th gear?

My offer via PM still stands too, at this point I will also get some WG springs to your door for free if you are going back to the dyno anytime soon.

This is making me worry I went the wrong route with my 7670.... still brand new in the box....

How is the curve at 15-18psi all the way?

This is making me worry I went the wrong route with my 7670.... still brand new in the box....

How is the curve at 15-18psi all the way?

On 15psi my set up would spike 18psi and settle to 15psi. I always had this kind of problem on my old set up as well running the stiffer spring in the Hallman MBC- probably need to change the size of the bleed hole.

I didn't try it with the soft spring in the MBC that always worked well for me because of the 13psi pump, 26psi race plan.

Obviously there is a big difference in boost pressure, but if one had to choose between the two plots, I would pick the 8374. Again I do want to see apples to apples comparison( no boost fade on your setup).

Well, we don't race dynos and the racing I do is mainly in parking lots, so response is the most important thing for me.

I do want to see your car on a dynojet, with bigger base springs, and more time spent on the tuning. I have two 7670s that I will be tuning shortly too..

I hope to clean up the tune for sure, but a Dynojet isn't available to me on a regular basis.

I might try the stiffer springs (they all come with Tial WGs), but honestly it is a lot of work to switch them out and its not the set up I will running anyways.

I will never be over 6,000rpm in 3rd or full throttle in 2nd over 6,000rpm racing anyways as the traction and space to do it isn't there.

Do you have a dynosheet of torque vs boost pressure like the one I posted?

No, I could get torque & boost printed out from my earlier session, but it won't read as high as your shootout #s. PM me the settings you used and I might do that at a later date or you could just run your #s in regular Dyno Dynamics #s corrected.

Also when you checked on the street was it 4th gear?

Yes.

Here is the Dynojet plot from earlier today.

Sucks they couldn't get a clean rpm reading... again.

Anyways, you can figure torque from roadspeed in 4th. Dyno starts a little before 2,000rpm and revlimiter is 8,000rpm.

419rwhp on Dynojet.

https://www.rx7club.com/attachments/...jet-9-7-14-jpg

This vid shows response in 5th, 4th, 3rd and back to 5th.

I don't know how it compares to 8374, but it is better than my 60-1 was.

https://www.youtube.com/watch?v=XpkJ...ature=youtu.be

That's crazy

i suggest you contact whoever did your dyno session and ask them to send you something of actual value to you and the club.

1. change the X line to Engine Speed

2. click on "Correction Factor" and choose SAE. almost no one would offer a dyno sheet uncorrected. further while i am on the subject any time you see STD as a correction selection you should know that someone is simply wanting bigger numbers. the difference between SAE, which is the OE standard, versus STD is 2.55%. at 500 hp that inflates output by 13 hp merely by using different temp/hum and pressure. so if you want more hp use STD but know that your number is inflated.

3. given you paid for the dyno time you should also ask for a boost plot (v rpm). the best way to portray boost is devoid of other data so it is not minimized. a boost and torque would also be helpful.

just as a note to others, if you download the Winpep7 software you can then ask for the entire dyno FILE. you then can examine every data point, you can compare different runs on your computer etc. if you used the software you could set up your own page, w whatever factors you wished and then post it as a jpg/clean screen save...

you are to be commended for purposely sizing your turbo for your specific objectives. it is now possible to fit a turbo as perfectly as a custom made suit. once you get it tuned out i will be interested in your lower RPM traction. i do think this will be a factor w the EFR turbo line going forward. (maybe not a bad problem)

i did look at your video and if i was reading your AFR correctly it seems like you are quite rich in boost so there is probably a bit more power available.

i have a dyno file of 72 plots all corrected to SAE that posts power at 500 RPM intervals from 5000 thru 7500. (power under the curve wins races.) i will be very interested to see where the EFR line apportions power thru the rpm band.

hc

Thank you for sharing. Did you make any adjustments on the tune for the dynojet or just another pull( zero changes vs the DD).

Good stuff, keep it coming. In comparison to my 6266 on my FC with my very conservative timing you definitely have more response below 4k, but after that it looks to be about the same. I have some videos floating around that show the response. I will say that the precision turbos seem to make more power per psi than the EFRs but the response of them haven't been jaw dropping like I've seen on some of the EFR results.

There is zero power difference between the EFR & Precision turbos from what I have seen( same car, same boost pressure, same dyno etc).

Well Howard, I have to crash a diesel day dyno contest where they truck a Dynojet 150 miles once a year to get Dynojet figures.

I wait from 9am to 4:30pm watching diesels dyno and MAYBE get a chance to dyno if the operators are feeling up to it when the last diesel has run.

They run an optical pickup (diesel) and my crank pulley is too hidden by the fan shroud and undertray to get a reading.

So, I had them switch to the inductive pickup which I put on the plug end of the leading plug wire and asked them to set the pickup to 720 degrees. After his blank look I told him to set it up as 6 cylinder. He said he wasn't getting a clean enough signal and ran it in road speed.

The weather station stats are right there on the bottom of the sheet if you want to calculate it as corrected.

I will have to calculate the torque line by gearing and tire height.

Thank you for sharing. Did you make any adjustments on the tune for the dynojet or just another pull( zero changes vs the DD).

There was no adjustments between runs.

They didn't even have a fan in front of the dyno; the lowest run was actually the second pull.

After that 2nd run I asked my friend to spray my oil cooler and IC with my water sprayer. As you can see from the time stamps, just 30 seconds of that (roller decel took 30 seconds) and the HP recovered quite well.

once you get it tuned out i will be interested in your lower RPM traction. i do think this will be a factor w the EFR turbo line going forward. (maybe not a bad problem)

This is an interesting topic on the EFRs.

I actually find that it is much easier to maintain traction.

The old turbo went from having no power to full power over a shorter rpm span and so spun the tires up easily. The EFR starts right out with great power, so you don't have that sudden increase shocking the contact patch.

In addition, with the EFR and its BOV integrated into the anti-surge slot you can get any boost you want by varying the throttle position. It doesn't drop boost when you let off the throttle like my old turbo.

This means you can precisely backpedal to maintain traction.

Not to get sidetracked here, but the highest number efr 8374 I've seen have been from you which was 486 rwhp at something like 26-28 psi. A similar sized 6766 makes that at around 20-22 psi but give up some spool and the broad power band that the efrs are showing.

For example of 6766 numbers, post #43 & 48
https://www.rx7club.com/single-turbo...1023860/page2/

8374 would be a 6265 in precision language. Also the car has high RPM misfires, so PEAK HP numbers are way down. @ 5800rpms right before the misfires start you can actually see the torque curve is still climbing at roughly a 60 degree angle. It was probably on its way to 470FT lbs. HP is just torque x rpm. If the misfires weren't there it would probably be 550-600rwhp( assuming no other restrictions/issues).

Take a look at this link with a 9180( Which is roughly a 6868 PTE- Not that they make that size but for size comparison) make 57xrwhp @ 20psi;

http://blogdotturbosourcedotcom1.fil...vs-s366-91.jpg

I need to update the blog as I have a ton more info with more dyno sheets etc...

Wow, yeah keep the dyno sheets comin, that's good stuff :icon_tup:

Here is a JPG of the Excel sheet/graph I made using formulas for mph to rpm and hp to torque. It lost some resolution as I only graphed every 2.5mph.

Actually made a tad more torque than horsepower @ 419hp/423tq.

It is uncorrected Dynojet #s, but I ran the weather station stats and it is .983 CF so my #s are only 1.7% over the corrected values.

You can really feel that 300ftlbs @ 3,000rpm when you are driving/racing. I did some drag racing Saturday and I could bog the launch so I was starting with a roll on and still run low 12s. Best times were high 11s.

It was so nice to pull the V8s on shifts instead of dropping behind waiting for boost.

Click and zoom for larger image
https://www.rx7club.com/attachments/...s-efr7670x.jpg

What MPH?

The only slip I have is for my third run and first 11 ever which was 11.9 @ 118mph. Spanked a C63 AMG with my 1+ sec reaction time :lol: (I'm no drag racer!)

My friend watching said I ran a 11.7 later as I got more practice. Didn't catch mph.

I think I will be able to get 119mph pretty easy if I haven't already and might squeak out some 120mph with a fan added to the IC for grid and practice shifting.

of course i couldn't let that data just sit here... thanks for it BTW.

i pulled out your power at 6 RPM points

5000
5500
6000
6500
7000
7500

and added your results to my other 71 dyno power outputs each w the 6 data points.

your total power under the curve is 2379.

i then took the 5 runs above and below 2379. the ten averaged 2373. i averaged the ten which are the red line.

the X line point one is 5000 RPM, point two is 5500 thru point 6 which is 7500.

we have a new animal here.

the big question is what happens to the blue line after point 3 when you get your system running 100%.

http://imagizer.imageshack.us/v2/xq90/903/0pql7O.jpg

howard

120MPH is pretty good! I think I trapped 124MPH on my 07 GSXR 750( no drag launch, and I don't drag race bikes).. Thank you for sharing the dynojet graph with torque curve. Regardless if its over inflated numbers, its what MOST dyno systems use as base in the tuner community. All of my dyno charts that I have personally tuned have been based off of dynojet numbers, so I keep it consistent to compare.

That response( torque output) definitely beats the 8374.... Good autoX choice. We have a 7670 IWG FD kit leaving in the morning...

he big question is what happens to the blue line after point 3 when you get your system running 100%.

Honestly, after I get my final tune I think the only difference will be a straight line drawn between 4,860rpm and 7,221rpm (the too rich to read on wideband area).

The whole concept for my set-up is being able to easily switch between pump gas boost and race gas boost- so I doubt I will ever put in the 21.75psi WG springs.

I still have to make the collar clamp for my MBC to bottom against on the high boost setting before I can turn the boost down (lazy!)

Sorry, for that bad news.

The good news is *only* 400rwhp Dynojet is still good for a 57mm turbo on a rotary. Plus, that spool!

Very nice area under the curve.. that is the 1.02 AR housing right?

Does it feel like spools a lot faster than the 8374 with the .92 IWG housing?

Your intcooler setup looks also nice.. do you have a photo of the hood?

Would you prefer this setup over the twins in carving through the mountains?

Hot damn. The response in that video is incredible!

Very nice area under the curve.. that is the 1.02 AR housing right?

Does it feel like spools a lot faster than the 8374 with the .92 IWG housing?

Your intcooler setup looks also nice.. do you have a photo of the hood?

Yes, the 1.05 AR T4 external WG housing.

Regarding the 8374 .92 VS 7670 1.05, we will have to wait for someone to do an in car video of 3,000rpm 5th gear pulls with the 8374 as I did (My stock tach is optimistic, subtract ~300rpm @ 3,000rpm).

I will take another video of the Haltech Engine data page while cruising/pulls.

The boost response at low throttle positions is really good which helps the engine feel like it has more displacement. I noticed right away that the car just drives around town at low rpms a little easier.

I do think the 8374 looks like it fits the rotary better as the dyno plot is still recognizable as a rotary engine (for better or worse).

I think the 7670 will appeal only to those who insist on the ultimate in turbo response without choking out the engine with a restrictive hotside or putting up with the "finicky" sequential twins.

Sadly, my hood is still a stock NA hood.

Would you prefer this setup over the twins in carving through the mountains?

At pump gas boost on the EFR (10-13psi IMO) I don't think I would notice a difference between the EFR 7670 and sequential twins in my FD carving through the mountains. I have the secondary transition set seamless with the dual Hallman Pro RX boost controllers though.

I don't know who would cruise though the mountains on race gas boost (14-? psi), but I can tell you that even with *just* 19psi @ 3,000rpm the EFR torque is incredible compared to my stock sequentials and by the time it hits 26psi @ 3,300rpm I stop trying to even make comparisons to the sequentials and start comparing it in my head to an LS V8.

But its not a V8, the turbo still has to spool (albeit quickly) on throttle tip in.

Around town and in traffic I feel the sequential twins still have more torque from 1,000-2,000rpm.
As I stated before I think this could be largely addressed using the stock 3rd gen exhaust manifold as a quickspool valve with the EFR (but then you start to get into the exhaust heat soak issues just like the stock twins...)

You do get about 5-7psi boost free revving in neutral near redline and letting off like with the stock sequentials. I hadn't experienced that with my last single turbo set-up.

What setting were you running for the 11.9 @ 118 mph? I ran a 12.0 @ 116 on my BNR @ 15 psi. I assume this was your 13psi tune.

Nope, I am no drag racer!

On my old BNR @ 14psi-18psi *peak power didn't really change much as it was out of flow* (380rwhp on Dyna Pack & Dynojet- 325rwhp Dyno Dynamics) - I only ran mid to low 12s @ ~115mph.

I had to drive really aggressively to even get that. Good launch, flat shifts and a clean run.

On the EFR 7670 @ 26psi (419rwhp Dynojet- 369 Dyno Dynamics)- I only ran the high 11s @ ~118mph.

But, I could granny shift and get a so so launch and still run high 11s.

When I bogged the launch to 3,000rpm and missed 2nd I still ran a low 12. That is down to the 7670 response/torque.

I am sure I will get faster as I get better at the drag racing thing.

I assume this was your 13psi tune.

Nope, the EFR 7670 isn't making nearly as much peak power @ 13psi as the 60-1 since it is a slightly smaller and high pressure ratio oriented compressor.

13psi on the 7670 is ~275rhpw on the DynoDynamics from what I remember, but would be ~320rwhp on the 60-1.

Hell, the 60-1 really surprised me by making 295rwhp on the Dyno Dynamics at just 10psi PEAK boost. That would be ~ 330rwhp Dynojet @ 10psi from my experience.

But that lag... Peak power isn't where its at for the racing I do.

I wanted that LS V8 torque and the EFR 7670 (and race gas) delivered!

What are your AIT's like running that much boost with that turbo?

I didn't notice that IATs were abnormally high compared to my old low boost set-up. I will have to take a 4th gear log.

Last weekend was auto-x racing. I got to use full throttle in 2nd gear once for a second at the finish of each run :lol:

My Intercooler was still chilled to the touch on the coldside and warm on the turbo side after my 1min runs (I spray the IC with water before my run).

Obviously, it will take a venue like a hillclimb where it is 100+ degrees ambient and 3rd/4th gear full load to really see the higher IATs impacting the IC with heatsoak.

Its probably time for a vented hood to take advantage of my horizontal mount IC set-up as well as a fan on the IC.

I am doing an "enduro" the weekend after this which is 5 laps on a kart track (4 minute sprint race despite the name).
I am also interested in seeing how the IC and radiator handle full boogy at 26psi.

Well, the kart track is all 2nd gear with 3rd down the front straight, so it likely won't be full load/boost due to limited traction....

Ok, now I need a widebody to put the hurt on my cooling system!

Thanks. It seems to be a tough choice between the 7670 and 8374! I know I want one, but I'm not sure which one will suite my goals better.

Good read, I am also doing a 7670 on my FD (From Turblown). I too am shooting for response, as most of my driving is just traffic light grand prix (occasionally) and I daily drive it. The response seems phenomenal in the video! I was looking to see how much boost you were running, to see what I could expect. I didn't want to crank it too hard, being daily driven I need it to last.

What injectors are you running?

you can run any injector and be fine. The sweet spot for this turbo is 20PSI in terms of efficiency at our elevation (6,300 ft).

at sea level the sweet spot is 24 lbs ish.

at sea level, you can run the turbo down to 18psi and still be in a good efficiency spot. (2.2 pressure ratio).

up in high country we can run 14PSI and still be efficient.

Good read, I am also doing a 7670 on my FD (From Turblown). I too am shooting for response, as most of my driving is just traffic light grand prix (occasionally) and I daily drive it. The response seems phenomenal in the video! I was looking to see how much boost you were running, to see what I could expect. I didn't want to crank it too hard, being daily driven I need it to last.

What injectors are you running?

Probably asking about injectors as I stated I maxed mine on the 7670.

I was running 2x 720cc and 2x 1600cc injectors with an in-tank converted Bosch '044. We could have leaned it out quite a lot and then raised the boost as it was running richer than 10:1 on the top end.

I ran 26psi on race gas and 13psi on pump.

The 7670 doesn't make great power at low boost (like 13psi), but it does get full boost very early on. 10psi@2,500rpm and full boost just after that.

On 26psi it was an animal.

I say was, because at the race I got a full day of practice Friday and Saturday and then Sunday it cracked the front housing pulling out into the street partial throttle in 2nd.

Haven't taken it apart to see what went wrong. It was full to the top with 110 as I had been running 110 and refilling all weekend.

The EFR 7670 basically added a gear I could use on the short kart track if I wanted.

On the front straight I could shift 2nd, 3rd, 4th if I wanted and it ran the same time if I wound out 3rd to redline. On the short back straight I could shift 2nd to 3rd or let it wind out 2nd.

It is easy to let it rev out a gear as the torque is dropping so it doesn't get hairy.

Shifting early at 6,000rpm or so feels great as it puts you back in the meat of the torque, but then you have to add the time needed to downshift.

Basically, I found the EFR 7670 made the car fast no matter how you drove it- very accessible power band and quick into boost as well as recovery.

You can make "mistakes" on your shifting and not be penalized or if sections of the track dictate when you are able to shift you won't pay a penalty in power delivery in other sections.

Here is a vid of a practice session on the kart track. I chose an early session as my driving is more entertaining before it gets faster.

https://www.youtube.com/watch?v=JSDd...ature=youtu.be

this is spot on here. When I ride in speedjunkies car its the exact same thing. wide great power in all gears, easy to drive, and I love how he can take a gear higher and smoothly pull through the corners. That little track would be perfect for this turbo. I couldn't imagine using a large turbo...the bigger turbo's in the thinner air here are worse to spool up. I think the smaller ones are better IMO.