finaly got out and dynoed my car. Making 330 hp at 15-13psi with the Apex kit. Most people are seeing 350, 360 at 15psi. For some reason I have to turn my boost controler way up just to get it to hit 15 and then as the RPMs go up I slowly creep down in boost to like 13-14. Now if I keep turing it up I get a bigger spike when the turbo first spools. Also my turbo spooled about 1K RMP later then it would on the street. This only leads me to beleave that there is less load on a dyno jet. Doesn't a turbo work better with more load ? The car revs so much faster on the street and just feels more powerful. The boost doesn't drop off on the street either like on the dyno. Does anyone have any idea whats up or do I have alot more tuning to do

 

Compression test?
Not enough tuning?


-Ted

 

The numbers coming out of a dynojet are affected by your rotating mass. If you have two cars with identical engines, but one of them has big diameter wheels, or heavy wheels, or big brakes, then that car will register less power on the dynojet dyno, even though it has the same power at the engine.

 

what air /fuel ratio are you tuning to? what range do you find execptable? 11.8-12.4 at sea level is a good goal, from what i know. Too rich and you burn up seals too lean and...well come on NO GOOD! Anyone feel free to chime in w/ a good range for peak performance.

Also expect better productivity on the street due to better cooling (air flow throught the IC and rad.) On the other side... More drag on the street (wind resistance) Yes i just contradicted myself and went a lil off topic but im trying to give insight to the free on street vs dyno.

 

If you are losing boost, check to see if theres a leak somewhere.

 

the issue with the boost only happens on the dyno, on the street it holds boost very well and can maintain 15psi with a lower boost setting also I have tested the whole intake from the turbo to the UIM for leaks and I only have a slight leak from the BOV, I guess possably the LIM could be leaking or the seal between the UIM and the LIM but I then why wouldn't I have the same problem on the street.

The A/F is different depending on the boost level, intake temp, water temp,... ect but if you mean for like WOT after about 5500RPM@ 15psi I'm gereraly shooting for a 11.5 - 12 . I'll try to get some runs posted up here.

The one thing I've never done is a compresson test and that could be an issue but I hope not since this motor only has about 18,000 miles on it and to my knowledge has never pinged or been run lean

 

Although I've never seen it, you could be right - the load from the DynoJet isn't enough.
Almost always, street loads are larger than the loads most DynoJets can induce (unless it's running that expensive load cell system).
Yes, turbo's produce more boost / power with more load.


-Ted

 

this just sucks, I put ALOT of time and money into this car and I finaly feel like I've got it right and then to only make 330hp feels like, whats the point. The car is fun, fast to drive, and resonably reliable I guess I should just be happy with it like it is for now or just sell it.

 

Stop worrying about numbers if you car is fun and fast to you. You already have achieved the main goal, the only one that matters.

 

true, i just wish there was a better explaination

 

24" dynojet is rated at 1000 hp, and the 48" at 1800 hp, so not likely you exceed it's capacity. which dyno was used? what gear? 3rd on the 24" might be too quick to keep load.

when comparing with street performance, are you comparing same gear? same initial rpm before going wot?

if the dyno run took less time than a similar same gear street run, then the dyno is providing less load.

 

The numbers are basically useless unless you're comparing it to another car on the same or identical dyno.
I don't use the dyno to go bragging about numbers - I use it to tune set-ups.
Go to the race track if you want to brag about your car.

A good point about the gear you were in - do runs in 4th if you want highest numbers.


-Ted