Curious, what AFR's do stock 7mgte's run at 7psi?

[nextproject]

I have nothing to base my wideband data on because i have no clue what the toyota engine is "happy with" regarding boost, so before i start increasing past the 7psi i currently have (only other mods are 3" elbow, 3" exhaust from the elbow back, open-element intake, fidanza fw, TRE 255 intank pump relayed to battery, egr delete w/ JDM ecu, no ac/ps).

I've got an innovate LC-1 with gauge and see anywhere from 11.5-12.5:1. Engine is performing flawlessly so far, i just thought that the afr's should be a little lower, but that may be other engines im thinking about, maybe the 7m is designed this way.

 

[Nick M]

9.5-10.0:1

 

[nextproject]

so im running lean.

 

[346fc3s]

12.5 is a perfectly safe number for just about any boosted engine I've worked with. I haven't worked with a 7M specifically but there are some general rules that apply. You may be running leaner than stock but that's not a bad thing, it'll make the car more efficient and make more power. Just keep an eye on it as you turn up the boost and if you start running any leaner than 13:1 under boost then you'll need to rethink things.

 

[supradjza80]

12.5 is a perfectly safe number for just about any boosted engine I've worked with. I haven't worked with a 7M specifically but there are some general rules that apply. You may be running leaner than stock but that's not a bad thing, it'll make the car more efficient and make more power. Just keep an eye on it as you turn up the boost and if you start running any leaner than 13:1 under boost then you'll need to rethink things.

hmm I would disagree with this. i would want 12:1 or lower under boost, ideally around 11.5:1. My car is in the 10:1 to 10.8:1 range when at stock boost or turned up to 17 psi. This was both on the Stock turbo and currently with the CT2657.

 

[GrimJack]

hmm I would disagree with this. i would want 12:1 or lower under boost, ideally around 11.5:1. My car is in the 10:1 to 10.8:1 range when at stock boost or turned up to 17 psi. This was both on the Stock turbo and currently with the CT2657.

Agreed. Now I'm no professional tuner, but I wouldn't take any forced induction engine near 13:1. My current car is still running 10:1, my 7M was 11.2:1 - anything more than that, you're risking thousands of $$$ in engine parts for a few extra ponies.

 

[super.secret.supra.club]

doesnt mines ecu for the 7m tune at 12,5 for responce

 

[nextproject]

hmm. i guess i need to try and figure out why its running this lean. could be the pump, could be the wideband sensor itself, could be the jdm ecu, doesnt the fuel pressure up solenoid raise fuel pressure during full boost situations? that may not be working, the only codes i've got are for speed sensor, a switching circuit (FPU solenoid wasnt named in the list of things that circuit powers) and ECT, although i've already checked that the ECT sensor gets 5v when checked with key on across the connector, and the wires have no resistance between the ECU and sensor. Could be a faulty sensor but i cant imagine that would let my car run this much leaner under boost.

 

[nextproject]

well i read up on how the FPU vsv system works and i dont think a malfunctioning VSV would cause me to run leaner at WOT, i'll disconnect the hose from the regulator and do a couple WOT runs to see if there's a difference.

I think the screw in the MAF was messed with, i got a used one on here, i guess theres a possibility it may have been adjusted improperly. I'll see if that will make a difference.

I also suspect the fuel pump because for a minute or three the pump was run with no fluid in the tank, to the point where slight smoke came out of the fuel hose, although it runs fine right now, it may have permanently damaged the pump's ability to flow enough fuel.

I also suspect the wideband sensor because while the car sat without an engine in it the wideband was hooked up and got some water on the sensor (ok alot of water!) and i cleaned it with brake clean and put it in my toolbox at work for 3 months.

I think i'll swap those two parts out over the next week and see where it goes from there, if my a/f ratio gets richer then i'll assume its safe to crank the boost a few psi. Headbolts were torqued to 75ft-lb.

 

[Supracentral]

hmm I would disagree with this. i would want 12:1 or lower under boost, ideally around 11.5:1. My car is in the 10:1 to 10.8:1 range when at stock boost or turned up to 17 psi. This was both on the Stock turbo and currently with the CT2657.

Agreed. Now I'm no professional tuner, but I wouldn't take any forced induction engine near 13:1. My current car is still running 10:1, my 7M was 11.2:1 - anything more than that, you're risking thousands of $$$ in engine parts for a few extra ponies.

As a former professional tuner, I'll tell you that I'd never tune a 7M for leaner than 12.3:1 on a dyno for a peak HP pull on race gas like C-16 or VP-Import.

For a street tune, never leaner than 12.0:1.. Even that is pushing it and would come with a lot of disclaimers for any customer who demanded it.

11.5:1 is a good safe "street tune" - any leaner and you're really asking for trouble, especially with the 7M - the super long head, weak HG design and the bimetal nature of the motor make this one you have to really be careful with.

 

[346fc3s]

11.5:1 is a good safe "street tune" - any leaner and you're really asking for trouble, especially with the 7M - the super long head, weak HG design and the bimetal nature of the motor make this one you have to really be careful with.

Good to know, I've helped tune a few RX-7s and they make more and more power the leaner you run them, some (not tuned by me) are running 13.5:1 or even a little leaner. You just have to be careful to make them not detonate but that's the line you have to walk to make power. I know this is the exception as it's a rotary, but we generally put cars in the 12-12.5:1 range under boost or 13:1 (roughly) for NA. This is almost exclusively on race cars however and I don't have any street car tuning experience other than my old 22R Celica which ran 12.1-12.5:1 under boost for 30,000 miles, including a few track days. The only time I had problems with it was at the drag strip one time when I did six passes back to back and heat soaked the hell out of my intercooler, I was starting to detonate at the end of the track and realized that my intake temps were close to 180 degrees. I added fuel but it didn't help and had to back down timing. Anyone running 10:1 to make a car run right is crazy rich and should be looking for other problems.

Edit: I'm sorry if I appeared ignorant but this is my first supra and I'm learning about it as quickly as possible. Like I said almost all my experience is with race cars but I will be doing a little with mine with a AFC Neo, hopefully in the near future so I'm lurking these threads.

 

[Supracentral]

Edit: I'm sorry if I appeared ignorant but this is my first supra and I'm learning about it as quickly as possible. Like I said almost all my experience is with race cars but I will be doing a little with mine with a AFC Neo, hopefully in the near future so I'm lurking these threads.

Don't sweat it. The only stupid question is the one you were too embarrassed to ask. These cars tend to be a tad different from the norm.

 

[tekdeus]

He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever. - Chinese Proverb