Pump Gas EFR IWG 8374 Dyno 14.5PSI
 

We rarely build cars here in house on pump gas anymore and I know a lot of guys don't have as much access to E85 as we do. A lot of guys are always bugging me for pump gas dyno results..

Here is a customer's car on stockports, pump gas 91 octane only. I remotely tuned it on CSmotorsports dyno with an Adaptronic FD PNP.
3" full exhaust(held 12 psi with controller off). I have it turned up to 14.5psi across the board. Not an aggressive tune by any means either. Between the street and dyno we have done probably 20-25 pulls.

Look like a very smooth build up of power. Any reason the graph doesn't show anything to 8,000 or 8,500 RPM to see how much it tails off at the limiter?

interesting to see that the torque is basically flat and holding from 3500-6500.

Stock ports are underrated.

I wouldn't mind seeing the same setup on various ports to compare the powerband.

My car should be ready to be tuned in the spring, my setup will be similar but with larger ports. I don't want to run meth so it will probably be around 1 bar of boost.

IRP stage 3 port
EFR 8374
IRP EFR manifold
IGN-1A coils
93 pump gas
PFC
A/C & PS

IC setup is the current unknown; my goal is to build a v-mount over the winter. If I'm not able to it will have an m-spec style FMIC.

Indeed. Very underrated. Clean the bowls, portmatch everything, change the closing just enough to get a smooth transition and call it done.

That is probably the most appealing BW graph I've ever seen, Niceley done Elliot!

Mimics my GTX35 hybrid with a full 4" exhaust. Flat torque from 3500 to 7200rpms. At that point it's not a torque curve but a plateau of force and anger that arouses me

You guys are out to lunch.

Look at the same turbo 19psi on a half bridge.

Instead of over 300ftlbs from 3,500rpm to 6,700rpm like the stock port you have over 300ftlbs from 3,100rpm to 8,500rpm.

If you knocked the boost down to the same 14.5psi as the street port it would make less peak torque (so not 160ftlbs more than street port), but it would still be 300ftlbs by 3,100rpm (this was just 14.5psi spring creeping to 19psi- no boost control).

https://cimg9.ibsrv.net/gimg/www.rx7...ceedb391b3.jpg

No... less really is not more.

And that looks like the typical BW graph... yeah yeah YEAH YES!!!!!! aweeeeeeeeee there goes the torque :(

So you really are complaining that the ported motor has more torque everywhere :uh:

If its too much torque in the midrange you can let off the throttle some.

If its not enough torque in the high rpm after torque has dropped you can shift or keep on it and remember, it is still more torque on the top end than the street port motor had...

Has the compressor wheel on the efr 8374 have any improvements since inception of the turbo?

Tuning4life Has the compressor wheel on the efr 8374 have any improvements since inception of the turbo?

Why yes.

111 years ago when the turbo charger was first conceived of (its inception date) there have been some changes to the compressor wheel.


https://cimg1.ibsrv.net/gimg/www.rx7...036312b7b1.jpg


By 1918 the turbo chargers were actually being used on aircraft- such as this Rateau unit GE used.

https://cimg1.ibsrv.net/gimg/www.rx7...8a8f211feb.jpg
The compressor efficiency was quite low as shown.

https://cimg3.ibsrv.net/gimg/www.rx7...7ad6f19d47.jpg

https://cimg6.ibsrv.net/gimg/www.rx7...41b6b1630f.jpg

The disk in the rear is the exhaust section where the exhaust flowed over the "buckets" on the disc causing it to spin and believe it or not that funky star shaped thingy is the compressor wheel.

Fast forward to EFR 8374 and the compressor wheel is indeed had some improvements.

I like the dotted line from just before 20,000rpm to after 22,000rpm.

From reading the historical accounts of these turbos- that is probably the range where it was most likely to spontaneously disintegrate the turbo rotating assembly.

The 8374 compressor wheel has not changed as far as I know since it was released. Although a new unit is in the works with a 67mm inducer(83 exducer). I have attached the map that was in the BW booth at sema... https://cimg7.ibsrv.net/gimg/www.rx7...c583381b1e.jpg

is it just me, or does that look very promising for lower boost setups at the expense of a bit slower spool?

My ability to read into compressor maps is not known to be good, so I defer to asking questions.

^Shawn, did you see anything for the 91mm setups?

BlueTII, I fucking love you buddy! Half-Bridge Powahhhh!

Very nice for pump gas. That torque curve is great. How much timing is it running at peak torque if you don't mind me asking?

Actually I didn't even look at the numbers, I looked at the curve and the shape of it. BW's always appear to be peaky to me, I was only commenting on the plateau of torque, not the actual numbers.

As for "knocking the boost down" that's all fine to hypothesize about it, but until someone actually does, one is still a 19psi graph, and the other is a 14.5psi graph. Not to mention the vast number of other differences that haven't even been talked about yet that can alter a dyno chart.
By the same logic I can say that back in the day I should've run my stock REW twins @ 19psi and I would've made 475rwhp.... but we all know that's just never going to happen.

Except at 3,100rpm where the Half bridge was already at 300ftlbs torque (500rpm ahead of the stock ports) the EFR 8374 is making ~14psi boost.

It creeps to 19psi boost at 4,700rpm for the 460ftlbs torque.

So unless I'm tracking you wrong Ian, your setup is set for 14psi but it creeps to 19psi by 4700 and then back down to 14 for the duration of the run? I doubt that after all you went through with the BNR you would settle for that.

This is why dyno racing is so pointless. There's too many variables unaccounted for so it's fruitless to compare because it isn't a comparison. The only real way to do it is take one car with an SP engine, tune it and dyno it. Then swap engines for a BP and repeat. Anything else there's just too many variables to get a read on the two setups.

No, that EFR 8374 half-bridge is Turblown's car not mine.

It is from this thread.
https://www.rx7club.com/single-turbo...19psi-1102573/

It was done on the Dynojet (unusual for Turblown dyno charts), so it was a good comparison for the stock port dyno in this thread and you can't easily mess with loading/spool (inertia dyno).

I did a little EFR 7670 on my FC and you are right, I wasn't going to take a chance on boost creep so I used two MVR 44mm wastegates on it.

Then swap engines for a BP and repeat. Anything else there's just too many variables to get a read on the two setups.

Except.... like in this case that does not work.

You put the same turbo kit on the half-bridge and it boost creeps because of the extra exhaust energy from dumping the air/fuel into the exhaust on overlap.

So then do you put a plug in the half-bridges exhaust to stop the creep? Is that an even comparison?

Or do you put external wastegates on the half-bridge? Is that an even comparison?

I feel that putting twin MVR's on and potentially open dump would definitely be more of a comparison. The key in my eyes would be getting MAP as close as possible between the two for the best comparisons of spool/torque

I'm wrong on the half-bridge.

The thread title and original dyno are 14psi creeping to 19psi.

The dyno chart I attached was stated-


300rwtq at 3krpms(15 psi)
400rwtq at 4krpms(22psi)
475rwtq at 4500rpms (24psi)
527rwhp at 7200rpms (20psi)

with a massive boost leak.

So...

I was out to lunch!

But you can see how the half-bridge torque hits 300ft lbs ~500rpm sooner than the street port.

TitaniumTTRE

I feel that putting twin MVR's on and potentially open dump would definitely be more of a comparison. The key in my eyes would be getting MAP as close as possible between the two for the best comparisons of spool/torque

I would agree with that as well.

14psi pump gas street-port vs 14psi pump gas half-bridge in effect would be the best comparison even though it isn't strictly apples to apples as far as supporting equipment required.

They are respectable numbers... and the boost control seems to be one thing that most people don't pay a huge amount of attention too which is why I feel alot of the BW graphs look like that. Boost ramps up and then bleeds off.

Yup, I can see that and understand why ;)

I would be curious to see what the boost looked like for the given torque. It's possible it's not a closed loop system with zero ramp up in duty cycle to hit the 1B mark. So the SP engine could only be at 10 or 12psi @ 3k where as the BP looking for 20+ is already @ 15psi... just playing devils advocate.