Hey guys, just got my car dynoed on a DD with my new Stage 1 (high flow cat, cam gears, downpipe) mail-in Xflash on 91 oct. It put down 264 whp. It pulls very hard up top, but the bottom end is softer. Both runs were done at the same facility on the same dyno at about the same temp. I have some questions for you guys.

1. There seems to be a 500-600rpm slower spool based on the AF Boost graphs. I have talked with Vishnu and I am waiting for Shiv's feedback. They have been very helpful. What kind of spool up are you guys getting with your Stage 1? By the way the dyno was set up the same way for both runs. Same ramp up and starting point.

2. What do you think on the HP and TQ curves compared to your Stage 1s?

I continue to be impressed with Vishnu's products! Thanks for any feedback!

 

I don't think it is spooling up later. It looks like they started the run at a different RPM.

 

How can you tell that? It looks like the torque curve starts at the same spot, about 1900rpms. The HP is so low that it is off the scale. Am I reading this right?

 

Anyone else have any thoughts on this? Maybe BOV?

I am beginning to think the ramp up rates between the two runs were different.

 

My first impression is the cam gear settings. Your tune looks to favor top end. I am not in the high low end torque camp for a small engine, I prefer to take advantage of the high rpm these little fours can turn (short, well supported cranks, low rod/piston masses) then let the gearing make the torque. Track your car as it is now then if you make a change please let us know what you find. If you go to more radical valve timming with higher quicker lift, longer duration cams, you will find there are a lot of options for crafting the power band to suit your needs. I doubt you have any problems at all, your charts look fine, cudos to Vishnu.

 

Basically what wildrice said. Its the cam gears. Although you trade some low end punch away, you get a ton more up top, where it really matters in any form of racing (except maybe dirt rally). The Stage 1 graph is much more desirable, and your car will be quite a bit faster like this.

The next step you should take is cams. You would put your cam gears about in the middle of stock and where they are now, as well as get more low end than you had on the stock gears, and about 10whp more up top. Enjoy it like it is now, I bet it a blast to drive!

 

your A/F looks like poo. i would fix that ASAP. your A/F should be a str8 line from start to slightly dipping near the end. the DD dyno is the most accurate out there so when you get that fuel tuned in, that car will be a beast.

 

Thanks for the positve feedback. I was starting to think something was wrong with my car because it doesn't hit full boost until 4000rpm. The power feels great above 4000rpm. It's the bottom that concerned me. I was looking at the Boost graph that shows boost hits at about 4000rpm. Most of the dyno graphs I have looked at show full boost for Stage1 and 1+ at 3500rpm like my stage 0.

It will take a custom tune by Shiv to fix the AF ratio. Maybe I'll get the cams and the TME 6.5 turbo and call it a day!

 

Shiv,

Any thoughts on the difference in the boost curves?

 

I honestly don't know. Boost is controlled with the boost fitting and is completely independant from the ECU mapping. So the problem is mechanical. My first guess would be cam timimg (off a tooth?) since gears were added just prior to that. My next guess would be a wastegate actuator that is cracked open for some reason. But you didn't swap the turbo so there is no reason to think anything happened with the wastegate actuator. My next guess would be boost leak but that's easy enough to see evidence of and I don't really see it (power loss up top). I'll think some more but for now, I'm a bit out of suggestions.

shiv

 

Thanks for the response Shiv. I'll double check the cam gears and take some pics. How do you check the wastegate actuator?

 

Here are pics of the cam gear install. It looks right to me. Any thoughts on this?

 

Your paint markings dont line up with the int side v/c mark?

Your int looks to be advanced by a tooth if the white paint marks are correctly applied to the "0" mark of the cam gears.

 

it looks fine the wide angle lens makes it look otherwise...

 

WOT,

Thanks just the way the Vishnu gears work. They are one gear off.


I tightened all the intercooler hoses yesterday. I am going over to the dyno shop to double check the way they set up the dyno for each run. Next will be the wastegate actuator. This really is a pain in the a$$.