Wanna bounce stuff off everyone.

I was making just under 400 wheel on my stock block on 9psi.
Greddy Twin Turbo
AEM Tru-Boost
Intercooler
3" TD custom exhaust.
HKS: iS
440cc injectors
255 walbro

Blew the motor because I had a pretend tune.


Now I built it: 8.8:1 wiesco pistons. [short block build]

And pretty much whenever I see boost (5.5psi+) I instantly hit lean. (Im talking mid 13s by 5krpms)

And this is with hours of tuning from roger @ japtrix.


Before I go spend my god damn money on a fuel system (which roger is preaching) I just want to make sure it all adds up. Does this sound like a fuel problem? I made more power (runnin stupid rich) on my stock block.

Now all of the sudden I can't make power or get fuel.

We found a broken gasket in my stock fuel pump tank- but fixed that up.


So 600cc injectors and a return line... or do yall think somethings wrong?

 

if u have a built block might as well go 600 or bigger with a return line. U can always do 2 settings on hi/lo boost. Do it right the first time or it's going to cost u more later on when u want more boost. I couldn't get more than 400whp with 440cc and return line and walbro.

 

That's good to know- That's kind of what I'm looking for. they way the IS tunes up. I can just change how much boost I run and it will tune keep the A:F just fine.

I'm was just thinking i'd be able to increase WHP 10-15 without any problem.. I'm pretty surprised.

 

Have you done a pressure test? Make sure you've got adequate pressure before you invest in injectors and/or rfs -- either I think will get you where you want to be however for maximum safety I'd do both and also get some sort of EMS like a UTEC to monitor knock above 5krpm (the factory ECU don't monitor knock over 5k).

 

Wow, you didn't even read my post did you?

I love that.

 

If you are running lean, and increasing the injector timing in the HKS F-CON is not bringing the AFR down, then it's either a fuel issue (most likely) or a problem with the F-CON (highly unlikely).

You had more HP in the stock block with the same amount of fuel because you had higher compression. You can go here and plug in your old hp and compression ratio and then plug in your new compression ratio:

http://www.bgsoflex.com/crchange.html

I already went there and did it. I arbitrarily assumed that you had 400 HP in your last build. I entered 400 for the old HP and 10.3 compression as the old compression ratio, then I entered 8.8:1 compression for the new compression ratio. Here are the results:

Engine Horsepower (peak) is 400
Old Compression Ratio is 10.3
New Compression Ratio is 8.8
Computation Results:
Computed New Engine HP is 383, a -4 percent change

Also, alot depends on the temperature and humidity when you dyno due to weather corrections, etc. Moreover, if I remember correctly, this block is still fresh. Everything is still a little tight.

Since you now have a built short block, you already have the Greddy TT kit, get the right fuel system. I don't know what cams and exhaust you have, but right now your bottleneck is fuel.

Last thing, you can very well have enough fuel flow to run rich at 3000 RPM while not having enough fuel to achieve the proper AFR at 5000 RPM.

Also, remember that running a little rich is generally considered to add a margin of safety to the tune, unless your so rich that you are washing the cylinders, which starts to occur somewhere around 8:1 and below.

 

OK, maybe you didn't read my answer or maybe I didn't state it clearly enough.

Yes, you need injectors and a FRS

Cheers

 

Terry is absolutly right the lower compression takes more boost to make the same amount of power as you did before. So you are most likely running out of fuel. If you want to make usable power from that new motor get your self some bigger injectors and a full fuel system.

 

either way, for a built motor. def go w/ some big a$$ injectors and a fuel return, then you'll be good to go for 500rwhp+

 

440c are pretend injectors on a built turbo motor.

Since you have a FCON, I;d go straight to 800+cc low impedance injectors, maybe even the 1000cc HKS.

 

+1 on the injectors. 440 is fine if you always drive in the Arctic, in Florida in the summer they aren't going to be close. Good info from TTG! I'm fine in the winter, but in the summer I try not to go over 5K RPM because fuel starts to lean out. (Canada)

 

Definitely get bigger injectors. And a return fuel system - make sure whatever you go with includes a 1:1 pressure regulator with gauge to monitor fuel pressure while tuning (if you don't already have one in car). At least that way, you'll have the fuel system on to make more power. And if the FRS doesn't fix the issue (although It should), with the gauge, you will be able to pinpoint if you have pressure problems.

 

The HKS 1000cc are very nice, but cost big bucks, somewhere around $1,200 for a set of six.

Also, the larger the injectors, the larger the granularity is. In other words, the injector on time is proportionally lower in a larger injector in comparison to a smaller injector. The F-CON (and I assume other common EMS's) only allow whole number changes to the injector on time. Roger was able to get my car purring like a kitten with the HKS 1000cc injectors, but it probably did take more tuning time.

In the overall scheme of things I felt that it was worth it for my HP goals, but I don't think Jtrain should push his engine as hard as me. From what I can tell, he wants his motor to last much longer than mine will. Always remember, the harder you push the motor, the faster something will wear out or break. It's the nature of the beast when pushing such small aluminum block/head motors with relatively small rod/main journals so far beyond what they were originally designed to handle. That's why you only see exotic cars pushing these kinds of HP levels. Even then, they are using titanium rods, valves, larger journals, etc., which gets extremely expensive.

 

8.8 CR with 5ish psi is going to feel like nothing. Roger is right, upgrade time.

If you don't mind mild hot start issues, get 1000cc injectors, skip the RFS and call it a day.

 

Denso 600cc Injectors, return fuel system, regulator.

/thread.

Good luck JTrain, keep that bish around 500rwhp and it will last for a long time!

-George
GT Motorsports