sweanders

I am sure that you can run a car with chips for other equipment than what is on it. A friend of mine has proof of that it can be done, a nice 3 liter block with an extra breathing hole in it. That car ran like a champ for a while with 2.5 liter chips and a K27/11 on the 3-liter engine.

streckfu's

What did his AFR look like? Did he use a fuel controller to adjust it? There is no way he used stock 2.5ltr K26 chips to run a 3.0ltr K27/11 without a fuel controller.

Drift is trying to assert that no changes are needed when upgrading to a larger turbo. I don't think your friend left the fuel system alone after changing to a 3.0ltr and larger turbo....

944Fest (aka Dan P)

Some details on Drifter's engine:
(Originally Posted by Driftomagnifico)
Sincerly,
Drifter
89' 240SX SRX #22
2300 lbs. + 550whp @ 15 PSI

It came up midway in this thread:
https://rennlist.com/forums/showthre...9&page=1&pp=15

I find it odd that he must have so much invested in that awesome engine, yet won't share a picture of it. I didn't call BS, but other folks did.

I now return you to the highly technical discussion already in prgress...

sweanders

Well, it didn't last long. But it did run.

My friend did not do the work, he bought the car with the blown engine in it and put a 2.5 liter in there again. It is an '86 Cup...

I have no idea of how the installation was done but I did swap out the chips and the FPR that was moved over to the 2.5 liter. The chips were the same type as those installed in my car when I got it (Superchips from 1990 or so).

I don't think that the engine was tuned at all, they just put all the things on there and bumped the fuel pressure (stock injectors were used) and apparently it ran very well until it blew.. I was amazed that they had used stock injectors and chips for a 2.5-K26/6 combo and not bothered to get the proper things. They were also using the stock wastegate and I am sure that they would have gotter more power, driveability and reliability with a MAF, turbo, injectors and chips instead of building a 3 liter engine. I guess they know now..

streckfu's

Hmmmmm.

That's the point of contention here. You can't successfully do it.

sweanders

My point (which may not have been very clear) is that even if you can run the "wrong" chips you might not notice until something goes wrong or you start tuning them.

Lots of people hot rod their Porsches and when it works they decide on a theory that would fit. Just read through the massive amounts of SC-talk on the 928-board and how many claims that the stock chips are fine - "Just up the fuel pressure".

Then one person got himself the proper equipment and started tuning the car (that already had been running successfully with a SC for months) he dialled out all of the small issues in a couple of hours and found power and driveability that wasn't there before. He also got out of the 10:1 AFR.

There is a difference between getting a car to run and getting it to run right.

streckfu's

The original post asked if new chips are necessary if upgrading the turbo. Drifto writes no and that everything will be fine. I can assume your answer would be yes.

sweanders

I don't know, I am not stupid/brave enough to tell him that it will work. Maybe it will work and it will all be fine but it certainly won't be optimal.

streckfu's

gcb951

WTF,
Where is this guys 600hp 951? I don't believe it if its not coming from Special Tool. We'll see.

jimbo1111

The answer is no. The stock and even some modified chips (APE) are designed to fuel with a dropping boost curve. If you use guru,VR or APE k27 afm chips than yes you can run flat to redline. The only limitation is your stock injectors. 300 whp is about the max you can run. Good after market turbos can make 300whp at 1 bar boost. 1 bar would be your limit with the stock afm and injectors. You can run more boost if you increase the FP but that affects the whole fuel curve and will make the motor run rich and sluggish off boost. And since no one knows the max cfm's that the afm maxes out. It's flat out stupid. BTW: Driftomagnifico is both correct and wrong. A k26/6 or 8 can not hold boost flat to redline at 1 bar. A turbo that can hold boost to redline and be above 70% efficiency will make very close numbers to a turbo that is 80% efficient at the same boost level. The reason a k26 will not make the same power is because it is totally out of the efficiency map even if it can hold 1 bar. The air will be over expanded with heat. Whether you run a T04E from 48,50,54,57,60, and so on you will make very similar HP at 1 bar. The 60-1 witch is the most efficient at low boost might give you 10 whp more. If even. When you run higher boost things start to really change. It is very important to know what boost level you plan on running. This will be the base from where you can go.

Porschefile

Thank you! Well put.

I apologize for the long posts, but let me try to summarize. What drifter and I are trying to say is that you would not have to retune your chips when upgrading the turbo AS LONG AS YOU ARE NOT EXCEEDING THE LIMITS OF YOUR FUEL SYSTEM! You will not have the most optimal fuel curve for your new turbo but, it will work provided you are not exceeding the constraints we are talking about. (boost, hp, etc exceeding fuel limits) This does not mean you can throw any turbo on and run any boost you want. If you are on stock injectors, you are realistically limited to roughly 300rwhp. That means with stock injectors, upgrading the turbo and not retuning the chips you would need to adjust your boost accordingly so you are not exceeding ~300rwhp and the limit of your stock fuel system. Does everyone get it now? If you've upgraded to 55# injectors and a 3bar fpr, then you should be safe to roughly ~350rwhp.

I'll see if I can convince Drifter to post his dyno sheets. It is an Sr20 Nissan 240sx.

streckfu's

So you guys are going to tell him that it OK for him to change the turbo without changing the chips or getting a fuel controller? Go ahead.

That's a ****ty way to advise someone on upgrading their car......

lart951

I am not a guru master craper like these guys, but I have to agree with you, changing to a different turbo without the proper tuning is bad advise.

AL951

Hello,

I have just done that. went from a K26/6 to a K27/6 with the same APE chips. I am running the same boost as before 14-15 psi ,3 bar FPR and I can report on no plroblems yet. About the only thing I have notice is the my power has increase about 35-40 rwhp as recorded by my Gtech in car dyno.

Engine feels much more powerful at low revs and very responsive. I still want to get some type of chips that are correct for this application but for now I am going to enjoy my new set-up.

Regards,
AL