Paul's car has quite a long history. His car has been a study into what you can get from an SR20 with certain mods. I've condensed years of mods and tuning onto this page. It's now pretty much turned into "Paul's SR20 blog"!
All standard hardware
It started out bog standard when Paul bought it years ago. S13 SR20DET - auto. Paul contacted us to see if we could tweak the ECU for a few extra ponies. This was Stage 1. He did the usual stuff - decent exhaust, FMIC, pod filter. We wound up the boost and tuned the ECU to suit. Here are the results. Not huge numbers - but not too bad for an auto with standard turbo.
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| Power vs boost | Power vs AFR |
T28, Z32 AFM, 480cc injectors
Next step was the trusty BB T28 - along with a set of S15 injectors and Z32 AFM. Results were good but the auto was taking its toll on performance. The T28 was capable of 16psi but was still dropping off up top - probably more to do with the boost controller than the turbo. This was the first attempt with an EBC. Note also that the mixtures for this set up were extremely rich. Certainly not conducive to max power! We were still finding our feat with the tuning at this stage....
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| Power vs boost | Power vs AFR |
Auto trans mods
Next was a trip to MV Automatics in Blackwood for a modified valve body + torque converter. This was actually a very nice combo. It allowed the car to build boost at a standstill ("And how much tyre smoke will sir require today?") so it would really slingshot when the brakes were released! And the modified valve body made for positive shifts that had it chirping sideways just nicely on the 1-2 shift. Yet it could be driven around quite sedately - without any of the pain that usually comes with a hi-stall converter. Mixtures were leaned out to give the kind of power you'd expect from a T28 on 16psi, but as you can see from the graphs, a problem was developing. The torque converter would not stay locked up once torque got above a certain level.
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| Power vs boost | Power vs AFR |
GT2871R and 550cc injectors
This combo kept Paul happy for quite awhile. Well, more than the usual 10 minutes anyway ;) But inevitably more upgrades were to follow. In the form of a 48 trim 2871R - and 550cc injectors. Things kinda became unhinged at this point. Suddenly the extra power of the bigger turbo was a lot more than the torque converter could deal with. It made for some frustrating customers/dyno sessions - with some rather interesting curves resulting. The converter would lock up and then start to slip at peak torque was reached, then it would lock up again as torque dropped off in the upper RPM ranges.
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| Power vs boost | Power vs AFR |
Manual trans conversion
The car was only running a modified OEM converter and after consultation with a local trans expert the decision came down to either spending big $$$ on a "real converter" or going manual. The cost was going to be about the same so Paul went manual. Suddenly all the power was getting to the tyres!
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| Power vs boost | Power vs AFR |
HKS Step 1 cams
Christmas that year resulted in a nice set of HKS step 1 cams and they were duly fitted - resulting in around the 220rwkw mark on 16psi. Things were looking pretty tidy. We'd done enough tuning work to have it just sweet. Good mixtures, optimised IGN timing, good boost curve.
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| Power vs boost | Power vs AFR |
56 trim GT2871R
One last thing was troubling Paul. He had a 48 trim 2871R. Which had been purchased in the interests of boost response. Just how did those 56 trim units go? After receiving a decent offer for the 48 trim he found out. The answer is about 10rwkw. Although the car does feel quite a bit faster on the road.
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| Power vs boost (14psi) | Power vs AFR |
This car is still driven to work EVERY day. And it does the occasional country trip - returning good fuel figures. Who says you can't have your cake and eat it too?! :)
HKS step 2 cams and 740cc injectors
OK, there's never "one last thing" with this car. Actually I think Paul and I are a bad (read "good"!) combination. We're both keen to know what results can be had with certain mods to an SR, so when Paul calls and says "Hey Pete, I'm considering trying xxxxx mods to my SR - reckon you could run it up on the dyno if I fitted up the parts?". The answer is invariably "Hell yeah!". And so onto the next stage...
Paul happened upon a particularly good deal on some upgrade parts. He finished up with a set of HKS Step 2 (still 264 degrees lift, but with more lift) cams, springs to suit and a set of 740cc injectors. He fitted all this up, I gave the ECU a quick tweak for the bigger injectors and we took to the dyno yet again. Not so much for a tune (very little should be required) but more to just "see what she'll do mate". As it turns out there was very little difference. Bit of a disappointment. I didn't even bother scanning the dyno printouts...
The BIG power adder - E85
Things were a little quiet for awhile but I knew that Paul had been considering running E85 after all the stories he'd heard. He didn't grab those 740's just for the hell of it! So I was too surprised when he called to arrange a re-tune for the magical alcohol based fuel. As per usual the initial tune was done on the road using NIStune and my trusty Innovate LM-1.
Then it was time to do the final tune and get a power figure. We both expected a decent gain but what we got surprised us both. On the very first run we got 268rwkw! What the?? Yep, that's nearly 40rwkw gain. We just had to see 270 (it's a numbers thing....) so we tweaked the boost a tad (from 17psi to 18psi) and got 274. That's another thing with E85 - because it's so good at suppressing detonation, you can run extra boost without a problem. No sign of detonation whatsoever.
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| Power vs boost | Power vs AFR |
Needless to say it goes great on the road. Some things we've noticed about running E85:
- It smells great! I followed Paul home after the dyno session and it has a distinctly sweet odour.
- The car is actually quieter while cruising. Hmmmm. There's one I wouldn't have picked!
- Top end power is increased. Have a look at the graphs - without E85 power actually starts to taper off around 6500 (typical SR). With E85 it pulls to at least 7000 before even looking like backing off. The same has happened on other E85 tunes I've done. Gotta be the extra timing you can run with E85.
- You really need big injectors - Paul's 740's were going to 90% duty cycle.
- Fuel economy does suffer. Deal with it. Overall fuelling was increased 28% when we went from "normal" 98 RON fuel to E85. You can lean E85 right out at cruise to help but I've not done a lot with this.
Update
I've been speaking to a lot of people about E85 lately. Everybody agrees that it's an amazing performance fuel. But you do need to be careful when changing over. Paul found that his car was leaning out due to low fuel pressure and managed to sort it out by changing the fuel filter. This seems to be a common problem as I've heard the same story from other people. Obviously what's happening is the ethanol is causing any moisture (and probably other rubbish) that's in the tank to go into solution rather than sitting in the bottom. This then goes through the fuel system. Most people just change the fuel filter after the first tank and then all is well. If you've got a lot of rubbish floating around in your tank then it could also cause fuel pump failure. Although I've only seen this once.