rx7srbad

Boost leak fixed and a successful test run confirms the Garrett TO4Z Turbo is now making almost 20 psi of boost at only 3886 rpm with repeatable performance. Looks like the TO4Z still has surprisingly good response on Tim's monster street port engine and almost comparable to the newer borgwarner turbos.

All that remains to be seen is the power this turbo can produce at 1.4 bar of boost.

rx7srbad

Managed to fix my abs system which has been faulty since 2018; full credit goes to Tim from RX Motors who helped me fix my boost leak and also diagnosed my abs system fault. Looks like my abs pump and abs control unit were both faulty and with those replaced and the abs system is now fully functional. I have more confidence stomping on my brakes in these cold and sometimes treacherous conditions.

This is Tims own semi pp motor running a conservative 450rwhp and revs to 11krpm and does a 10.5 quarter mile. Sometimes I wonder why I played it safe and only went for a large street port. Tims semi pp runs 1.3bar without wmi and on ordinary fuel with premix.

rx7srbad

• Feb 19, 2021 - The weather was dry today so I went out and solo mapped the car to 1.2bar and I can confirm its an absolute riot to drive. 4th gear WOT it totally hauls ***, almost scary enough for me to come off the throttle.

Making 1.2 bar of boost by 4krpm and the turbo seems like its awake for a change. Got some final tweaks to do with my boost control strategy and clean up the fueling a lil bit more....but extremely happy with how it feels. Once I dial in the 1.4bar map, i'll get some power runs completed on a dyno near me and get some dragy gps runs in as well.

rx7srbad

Feb 24, 2021 - For the time being I'm very happy with the high and low boost maps and everything in between....so wont be making any more tweaks with the maps until 12th March. Be interesting to see if I can get close to my 450rwhp goals and see what kinda power it actually puts down.



In the interim, the left headlight cover has been a victim of all the power pulls Ive done road mapping and dialling the car in.



Ordered a replacement set of concept 7 covers which I've already dropped off to my local body shop...so I should have the new one's fitted before the weekend. I've been told the side fitment is not the best....but looks oem fitment on closed position.

Next thing to do is to fully overhaul the underside and interior. I've been putting this off for year's due to the rotary unreliability of my 2nd rebuilt engine. However, thats in the past now and Tim has built me an amazing motor and restored my faith in rotary power!

rx7srbad

• Feb 25, 2021 - The weather must be improving as it was another dry and cool day.

So instead of waiting for the dyno day, I took my trusty laptop and upped the boost to 20.7 psi; approx 1.42bar. The car feels incredibly quick and mega responsive from 3.5k to redline; butt dyno suggests zero lag as it just picks up and goes.

Will clean up the fueling a bit more but it's pretty much sitting on the money.



I can only imagine how good the newer EFR turbos must feel on transient boost response where I can see mine takes time to build max boost again after a 3rd to 4th gear shift while in the boost window. I suspect this is where the EFR turbos must shine?

Were it not for this logging data; the butt dyno would suggest there is no lag and that's how it will feel for the vast majority behind the wheel.

Below is an example of an earlier log I did while dialing in the boost.

On these logs it's evident 3rd gear shift from WOT into 4th and although in the boost window the turbo does not make max boost instantly...it's building back up to max boost. I suspect this trend will be much worse on older, bigger and non efr turbos.


EFR and SXE owners - I'd love to see some data on this please? does your EFR instantly spool to max boost once 100% throttle is applied post gearshift?!?

rx7srbad

• Mar 6, 2021 - Made a quick run to Tim's today.

Lawrence's car turned up for a engine refresh.


Incredible to see it in the flesh and its the only rotary I've seen making crazy power on a compression of 3s! I saw the compression test results and still couldnt believe how it was producing north of 600bhp with compression so low.

Tim fitted some 850cc primaries in my FD for the much needed breathing room I desperately needed for running 1.4bar+ of boost.


Also used the BGW for what it was designed to do.





Think Tim may have a slight obession



DCT conversion also coming along...in a 450rwhp ish RX7 the pull should be relentless and still have complete refinement without any additional NVH.

rx7srbad

• Mar 20, 2021 - Finally mapped the rx7 on a dyno dynamics rolling road dyno...all went really well...except I noticed an issue with diff fp dropping slightly but afrs were comfortably south of my target. Spoke to Tim at RX Motors and he ordered a new fpr to sort this out. Def have a flow restriction issue with the high boost run.

Made 410rwhp and approx 400 lb ft at 1.4bar....tuned with water injection to 10.6afr. Low boost 0.8bar made approx 357rwhp tuned to 11.4afr.

The dyno operator had issues syncing the dyno tach to mine. I asked him to rev out to 8k...but dyno for whatever reason was only reading to 7k. Pinch of salt and pepper application required.

Anyways, we dont race on dynos so I will do a dragy gps 100-200kph, 60-100mph, 60-130mph if weather permits to see what the real world performance is like for the high and low boost settings.

All in all not a bad result for an ediot with a laptop . Drove to dyno, mapped it, drove home. I was expecting it all to blow up in my face....but did a full send rob dahm style !



Just to confirm the results...i went to another dyno. Different days....Different dynos but both high and low boost settings tracking virtually similar results. 0.8 bar 350rwhp and 1.4bar 400rwhp. So I'm pleased with that.



High boost approx 400rwhp

Approx 350rwhp

Got some 60-100mph dragy gps data to test real world performance between the 2 boost settings.

60-100mph is a great key performance indicator as this is where most motorway battles or rolling pulls on the street will be done and in most stock rx7 gearboxes this will be 3rd and 4th gear WOT pulls. Below are the results.

I will also gather data for 100-200kph and 60-130mph dragy gps data soon. Just need to find better private roads in Mexico.

In summary, low boost 350whp does 60-100mph in 4.85s, 400whp does it in 4.02s.


Low boost 350rwhp 0.8bar


Approx 370rwhp - 1.2ish bar (my previous dragy gps data is for 1.2ish bar or 370rwhp.


High boost 400rwhp 1.4bar

rx7srbad

I have a spreadsheet with dragy gps data.

As you can see a stage 2 M3 and stage 3 M4 is still faster than a 400rwhp rx by a decent margin for 60-100mph performance...but they also have more power and a DCT gearbox to boot! The Stage 4.5 GTR is basically on a whole other level for 60-100 performance. Even a 700hp M4 cannot match the raw performance of a 700hp GTR - Godzilla is a magical number generator.

I need more RX7 data with 450rwhp, 475rwhp and 500rwhp. Be interesting to see where these would stack up.

However, lets look at some of the positives... strictly looking at only 60-100mph performance.....a 400rwhp rx is still not something to be scoffed at. As confirmed below it is a touch faster than a fully track built 620HP E92 M3 and a lot faster than a 600BHP Ftype V8, OEM F10 M5 and OEM F80 M3.

rx7srbad

Went on a mountain run against a 700hp M4 and a stage 2 M240i and the 350rwhp rx did just fine in the twisties

However, as my dragy data confirms....its no match for a 700hp M4 and even with the M4s boost turned down to a stage 2 550hp on a rolling pull from 60-100mph the rx with 350rwhp is still no match.






Of course the stage 4 GTR behind is on a whole other level of 60-100mph performance. The 700hp M4 needs its meth map to compete .












As 1000bhp wasnt fast enough, my mates sent his car back to JM for even more power! The dragy gps numbers this thing was putting down was unbelievable...on par with hyper car levels.

All in all a fun and exhilarating mountain run for the 28yr old rx7 against some modern day weaponry.

rx7srbad

• Apr 10, 2021

• #231

After this run I got invited to a Aston Martin run at Brecon.



However, on my run up to Brecon mountains doing some 350rwhp pulls...i was going through a fast left hander and felt my steering get super heavy and unwilling to turn even....so I pulled into a layby and opened the bonnet and saw my crank pulley bolts had failed and I lost my power steering as the belt had come loose. Luckily I caught it early.

So that was a wrap for the day.....shame really as it was an awesome day!









Mate with the stage 2 M240i came back to show lots of love and support ha!








Recovered it home and got it back up and running the next day.

On further inspection it was the 4 bolts that hold the underdrive crank pulleys failed. 1 was missing, 1 broke off and 2 had come loose. Put everything back together and it ran even better than before. Likely the 28yr old bolts failed. Replaced all 4 with new bolts.

Also dropped the car off to Tim to fix the fueling issue. Also to fix my wmi issues thus only been running 350rwhp on all my runs.

After reviewing all my data it looks like my hks cast mani looks to be a restriction so I'm looking to swap to a 2" short runner mani and a 4"dp to remove all restrictions from my system. However, most shops are back logged so will have to wait for this to come to fruition.

However, I've discussed a few smaller improvements with Tim and he agrees.

So Tim's busy working on

1. Battery relocation to the boot wheel well with new cables and new battery terminals.

2. Wmi system wire into link ecu. This will make my life easier as I can have total control of my wmi via the link ecu.

3. Omp removal and tank removal for a bigger K&N air filter.

4. New aux belts and double check my fix on the pulley bolts.

5. Fuel pump hard wire with the new heavy duty relay and new aeromotive fpr.

6. Bigger Fuel return line.

7. New Heater blower matrix lines.

8. New bonnet catch release cable.

9. Engine, gearbox and diff oil service.

rx7srbad

• May 1, 2021 - Got the car back from Tim and it's working even better then it did before.

Made some small tweaks and relocated the battery to the boot wheel well.
New Fuel pump relay and wmi wiring refreshed.
Turbo refurbed and refit as there was a bit of excess shaft play Tim wasn't happy about.

Drove car home and noticed there was a oil leak from turbo oil feed. Found some damage to the Oil Feed Flange;


I'm not exactly sure how this happened but I wasn't able to get any replacement parts in time for the Caffeine and Machine meet today and although bitterly disappointed I could not take the rx I thought about taking the E92 M3 but ended up going in my brothers stage 1 140i as he's had a baby recently and didn't get much sleep so was safer to go in one car....but also cus 140i is faster then the M3 [img]data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7[/img]! Not to mention easier to drive and more comfy and refined.

Overall a very good relaxing day and a fair bit of hooning about and getting the back end to step out....these M cars and (140i) are beautifully tuned from factory if you can drive em.....I call em OEM drifters, soo effortless!



2 of my absolute favourite modern cars also turned up and the fly by these did was truly glorious! This made my day.
Huracan performante and 991.2 GT3 RS....one day!













Overall a fun day. Shame the RX couldn't make it but will be plenty of future opportunities. Me and my close friends have booked 5th October as a track day at Spa...so I'm glad these small issues are showing up now. Got pembrey booked too....so that should be a good shakedown event and a decent stress test!

If you havent been to C&M yet.....def go...even if you cant take the rx. Its super chilled and sociable and you never know what will turn up!

rx7srbad

• Aug 31, 2021 - It’s good when you follow your dreams, It’s better when you drive your dream but sometimes you run into issues and as ridiculously expensive as it is, I’m absolutely obsessed with my goal of getting to 450rwhp+. Once I hit that number and the dragy gps data can confirm the result....I will move onto...other things like the interior and underside restoration!

I was driving the car a few weeks back and noticed some oily smells from within the cabin and thought...well this is new! Something was not right. I had an MOT the next day and behold when we got the car on the ramp it was weeping oil from the turbo. Not so much that it was dangerous but enough for me to take the car back to Tim.

Tim took the turbo off and sent it to midland turbos who then rebuilt it under warranty. Seems like there were a few bolts they forgot to tighten on the turbo and fairplay, they took responsibility and fixed the issue very quickly.





This was the rebuilt Garrett TO4Z turbo sent back by midland turbos. While its a great turbo and spools really well....and made a good 400rwhp on my setup. It was time to move on.






Enter the new G35 1050. Similar dimensions as my old Garrett TO4Z so should be a straight forward turbo swap, remap and verify the results.

Garrett claim the G35 1050 as the name suggest is good for 1050hp! I'll be sure to put this claim to the test....their compressor maps etc...do look promising. So in theory, I should get to 450rwhp+ comfortably while being more responsive than the old 90s turbo and flow more. On paper it looks like its win-win, no brainer! Lets hope this is the case in reality too!

I have not been able to find any data of a G35-1050 on a 13b engine so as far as I know I may be the first rotary owner in the world to test this turbo on a 13b. Watch this space for real world results and no doubt more dragy gps data!

rx7srbad

• Sep 24, 2021 - Some progress pics.

Turbo swap completed and ready for collection. I've got short break at Snowdonia so unable to collect it until next week. Will aim to collect it as soon as possible.

Really looking forward to remap this and quite curious to see how much of the map I'll need to change to suit the G35 1050. Overall, really excited to see a current gen turbo replace the old TO4Z. I would say this was long overdue.

In the meantime, been looking at some different toys alongside the rx7 and as of late a couple of my mates recently got a Megane RS 265 Cup and I've always heard positive things about them. Personally, I've never been a fan of the original Megane but the design of the 265/275 cup and trophy are starting to appeal ever more then they did before. Might get one as a fun track car. They seem to be respected as a FWD machine at the ring alongside the infamous 911's and M3's.

However, do not worry the RX7 will always be the main focus. The goal is collect it, remap, verify the results via Dragy GPS....then move onto underside and interior restoration. I'm stuck on the interior seat choice, not sure If I should go Recaro CS or Pole positions!Reply

Sep 26, 2021 -
A welcome surprise from Tim today. Turbo Heatshield installed and all the coolant lines upgraded to stainless steel.

Looking forward to collect it asap.

rx7srbad

• Oct 10, 2021 - Finally got around to some high boost tuning today. Holding 20 PSI ~ 1.4 bar extremely well. The pull after 4krpm is incredibly strong and there is no let off until the next gear change....if the car had a DCT box the pull would be relentless! No idea on power/torque figures yet...no idea of dragy gps number yet either. Overall, very very happy with the new turbo and the tune.

The rest of the tune will be finalized when I get a chance to tweak it on a dyno. May even increase boost up to 1.7 bar if required. Quite keen to find out what the G35 1050 is doing at 1.4 bar compared to the older TO4Z.

12 PSI by 4300 rpm


20psi by 5000rpm.


Fairly safe tune for the road...and very consistent run after run. Called it a night here. Will get the final tune optimized on the dyno to dial in the final ign timings and afrs.

rx7srbad

• Oct 17, 2021 - Got a new daily - BMW 530D!

Made a frugal update on the rx. Installed an Aem inline filter for the wmi system. Tested and everything works perfectly. One less point of failure to prevent the injector from getting clogged.



Should get some dragy gps runs soon. Trying to get 60-130mph on high and low boost runs.

rx7srbad

• Oct 21, 2021 - Got the first piece of the puzzle arrive for underside suspension restoration. Got stung £70 quid for customs charges.

• Nov 1, 2021 - 2nd piece of the puzzle arrived today from JDM land. Luckily did not get stung by customs on this occasion!

Looks like the underside overhaul/restoration will be commencing soon!

rx7srbad

• Dec 6, 2021 - FD was dropped off to Mike at Stealth Performance early November to begin the underside restoration. Once it's done I have no doubt it will drive as good as new...hopefully better than new.

Mike didn't take long to get the suspension components off.


The underseal will be fully stripped to bare metal to inspect what the damage underneath is really like.



Mike advised to get the front discs changed asap as there were loads of micro cracks and a major crack which was very close to failure.

The plan was to powdercoat all suspension components but mike got them vapour blasted instead as most of the components were aluminium. They have come up like new or as good as new considering they are almost 30 years old.


Picked up a new banzai diff brace from @Ceylon


Got the Advan RG2 refurbed and they look amazing in the flesh. They are like new again. I'm so happy with how they've come out.


Overall the underside restoration is going very well. Hoping to have it finished by the end of the year.

rx7srbad

• Dec 10, 2021 - Rear Subframe dropped, fuel tank removed. Mike advised the rusty bits are surface rust and no major surgery is required.

Preventative maintenance being carried out with utmost attention to detail.


Rear shock tower - underseal removed ready for the next step.



Picked up the freshly refurbed Advan RG2s from Mike. Got some Gyeon G2 Rim to ceramic coat it over the next few days/weeks; whenever I get the opportunity to do it.




Overall, extremely pleased with how the underside restoration is going.

rx7srbad

• Dec 31, 2021 - Happy new year's eve everyone.

After the underside was fully stripped off the old underseal back to bare metal. It was repaired (where applicable) and treated with Bilt hamber rust converter, parweld zinc primer, raptor body sealer and bilt hamber cavity wax. I've been told by Mike it won't rust again for a long time.












Mike mentioned he had to repair 7 small sections with new parts and weld them in. I'm glad no corners were cut and the underside of this rx7s shell has been restored to its former glory. Mike mentioned he would wear a white tux for assembly of the underside [img]data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7[/img] . He's really looking forward to put it all back together.

rx7srbad

• May 6, 2022 - The underside has been reassembled. The rear sub frame's had some upgrades installed to aid strength and rigidity.

There's a few more bolts that need to be plated before I get the car back.
View attachment 32005

rx7srbad

• Jul 2, 2022 - Got the car back from Mike a few weeks ago. The extensive underside restoration work has been carried out. Its like driving what a new rx7 must have felt like without the knocks and bangs from the old and worn out bushes. Everything is tight and the ohlins dfv coilovers really tie it all together. The car feels great to drive.

Tell you whats now amazing right now is the ridiculous fuel prices. Makes me sick! [img]data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7[/img]


Back home and need to get alignment sorted and then get on with some boost and dragy gps runs.



Made it to Indigo GT where I initially dyno tuned the car...but this time it was there for a full alignment.

Some would say its a shame to drive it in the wet after a full underside restoration but for me....it was never a garage queen. I'm always gonna use it...every chance i get.....rain, shine or snow!






Unfortunately Mike did not get many pics of the masterful work he completed of the underside....so I managed to get some pics in while the car was on the ramp.




Seriously considering a new exhaust system !





Settled at -2deg negative camber front and rear.
0.5mm toe in front n rear
6* castor front

Felt really good on the drive home. Sharp, tight, responsive.

rx7srbad

• Jul 2, 2022 - So on the way back through some private roads I thought to test the low boost option, it was wet so the first run was a rather cautionary one. A smooth roll into 4th followed by granny shift into 5th.

12psi circa 350rwhp ~ 400ish hp.



little braver but called it a night here as it was bit too wet for my liking.

View attachment 32520

Tried again the next day....drier and a cooler. Made an improvement but not the kind I was hoping for. A 400hp RX7 should be doing a 100-200kph in sub 10s...so I did some data logging and found a few issues which I quickly fixed on the low boost tune.



The tweaks made to the map from the above data gathering exercise made a significant difference. 100-200kph in 8.94s was achieved going up an incline. This is a great result for 12psi circa 400hp power level. The tune in 5th is still very much on the rich side as evidenced below...so further optimizations can be made to the low boost/12psi map. I wont hold my breath for it to go much faster than this..perhaps a few tenths if i found a level road and leaned out the fueling in 5th


12psi 400hp 100-200kph in 8.94s. A lot better than 11s range.


Once I'm satisfied with tuning the optimal low boost map (which is dragy gps proven to be the fastest 100-200kph time). The inevitable next stop will be some 20psi runs to see what can be achieved for the 100-200kph. Its a promising start and the goal is to make it into the 6s range with 20-25psi. Looking at the data...i can easily save a couple tenths if i can somehow double clutch and not granny shift into 5th.

rx7srbad

Managed to go even faster. I think this is the limit of 12psi 400hp. I highly doubt i'll be able to beat this time.
I sorted out my granny shift to 5th and the results are better than i expected.


12psi 400hp and a 100-200kph in 8.52s is respectable, especially considering I had to do 2 manual shifts. If i had a DCT box....id imagine this would have been low 8s range.

rx7srbad

• Jul 3, 2022 - Finishing up the low boost map and tune. I decided to revisit the data and looked like it was just possible to hit 200kph at the very top of 4th gear (but I was being cautious and shifting into 5th for all my 100-200kph runs). So I decided to do one last run to test this theory and just made it to 200kph in 4th. Although a slight negative slope, dragy GPS deemed it a valid run and that's good enough for me. I suspect if the gradient was level...I would expect to be in the low 8s range (based on the data I have and also looking at runs I did going up slopes etc..)

Not a bad run for 12 psi circa 400hp. I keep saying I won't go faster and then go faster. However, this time I seriously doubt I'll go any faster than this on 12psi boost with the G35 1050. The conditions were great, the car performed flawlessly and the run felt effortless. I'll add all runs were done with a full tank of fuel or near full fuel weight. My FD is full-fat weighing in at 1,315 kgs with driver inc full wet weight.

rx7srbad

• Jul 6, 2022 - Final few runs to wrap up the 12psi map. 10*C hotter ait temps compared to my PB run and as I suspected low 8s runs from 100-200kph when the slope is bit more level. Starting to get a bit more consistent now with almost 20 runs ranging from high 7s range to low 8s range depending on temps and conditions. Overall very happy with the 12psi map including performance and most importantly the reliability.

Next step is to get to 14-14.5 psi and test to see if there are any worthwhile performance gains to be had over the 12psi boost setting. If it drops me into the mid to high 7s range consistently for 100-200kph, than it may become my new low boost setting without the need for wmi etc. That being said, in the wet 12psi 3rd and 4th are scary af but in dry conditions I dont mind going upto 1 bar provided the gains are worthwhile.