Ok, I know that on 3 kits are not very well liked by some on here, but want solid, real advice by some who have experience. My car:

1996 cobra
VT competition longblock 8.5cr
MPt70 .68 a/r
3.5" piping from hotside to dynomax race bullet with a dump
12.5psi

509hp @ 6200
438tq @ 5600
I am not seeing full boost until approx 4k rpms.

Does this seem a little slow on the spool time, and doesn't the tq seem really low?
Is this because of the slow spooling? Exhaust leak? Ideas? I know that dyno numbers aren't everything, but I was expecting tq to be in the 550ish range

 

Engine dyno? Chassis dyno? What transmission? Stall? Neeeeeeed more info.

 

exhuast?

 

keep an eye on that flex joint, my buddys got a new on3 kit and the flex coupler fell apart on the inside after about 500 miles of driving. he has since cut it off and welded on one bought from vibrant performance



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mustang dyno, t56, 3.73s in the rear

 

You should switch out those 3.73s and try that first.

 

Did they have the eddy current mode on or were they using it like a dynojet?

 

eddy current

 

If you ave exhaust leaks, yes that will hurt spool. But that's is about par for that kit. Gears will help. Check your wastegate. Those things are always leaking at the diaphragm.
No, it's not well liked, nor he. But you will still get all the help we can provide if you aren't a tool like some of the former. Your good so far.

 

The only exhaust leaks that would hurt spool would be those from the manifolds to the turbo, correct? I have a set of 3.55s that are slated to go in the car shortly, but I honestly just want to drive the car for a month before the weather gets too cold, and worry about it in the winter. As far as checking the wastegate, how would I go about doing that? The car on one pull spiked 19psi, and when he let out of the throttle at approx 5k, I heard the bov very distinctly. all of the other pulls it was kind of faint. does this mean anything to you all?

As far as the on3 kit, I had great dealings with chad, and although I can not give a review on the kit yet, chad on a personal level is a good guy. That however is very far from why I am here. I just want to get my turbo boost on I appriciate everyone's help already. As long as I've been into mustangs, (my 5th now) i've wanted one with a turbo and a 6 speed, and i finally have it.
I had a vortech s-trim on the car before, and on 15psi, i made 491/397, with far less under the curve, so i am already making a good bit more than with the blower. I just want all I can get out of it before I go switching to a different turbo, or spraying the car, or upgrading the fuel sys, ect...

 

Any leak before the turbo will cause a slow spool. And if you spiked to 19, I'd say the wastegate isn't working.Take it off and apply regulated air pressure you it and listen for leaks. If it's leaking, most of the time the back pressure isn't enough to open the gate. So you need the pressure from the line attched to the bottom port. If it leaks, the valve doesn't bleed and you get over boost.

The BOV could have been there, and you didn't hear it, not enough boos to open it the other times, or the spring can be too tight.

 

When it spiked, it was because the wg was on an 11psi spring, and we just attached the boost controller which was set at 8psi. I should have been more clear. But as far as applying regulated air, would i do this at the top port on the wg, or???

 

Either should leak if there is a problem. But bottom, since that's what opens the gate. Just to decrease variables, apply it at the bottoms so it's just like when it's in the car.

 

idk man, from what I've seen those on3 kits spool really late. There's a big nutswinging thread on corral with the guy that got banned from here, and he keeps pouring $ into and it's not helping that 4k spool time. From all the dyno sheets, and what I've seen a lot of them spool really late, with the china turbo and the MP. What's the a/r of the exh side of the turbo

 

I've noticed the same thing about these kits. Not just the on3 kits but all the stock manifold retaining cobra kits. I think it's header design.

 

I guess the reason for my concern is because why on3 did the dyno testing on their 99 in house car, it did 526/550 on 10psi. I know that i am down on power from having a lower comp ratio, but would still expect to be near the 500ft. lb range with the tq on the car. esp bc i am at 12.5psi.

 

Apples to oranges... You dyno'd the car on a real, eddy current dyno. All their dyno stuff is on trash dynojets. Dynojets always read stupid high compared to most other dyno's (mustang/Dyno Dynamics etc) Dynojets usually run 15-20% higher in some cases... That's why it's amusing when companies like On3 come out with subpar products, and put it on a dyno and inflate the numbers... Most people don't realize the DJ reads a bit higher, and are humbled when they get it on something more accurate.

Does the T70 have the .68 ex housing? Are you using a manual boost controller? Does the car have a solid tune on it? If the car isn't tuned well it can def make for slow spool up. You may want to pressure test the coldside for leaks as well... It's not tough to make a pressure tester out of pvc pipe cap end and an air fitting, use an adjustable air regulator and pressurize the system till you find the leaks. We did this on my buddies car, thought everything was fine except every single t-bolt had to be shimmed because they were leaking at anything over 5psi. Fixed that along with some other small stuff and it doesn't leak up to 40psi

IMO the gears and whatnot aren't going to matter much. That T70 is a pretty flexible turbo, and on a 2900lb car with a GM3800 it's hitting full boost ~3400 with stupid short gears (even has to shift into 5th at the track) so I don't think you can point to the rear gear as the problem. Realistically you could short-shift the car to load it earlier and once it's loaded it should hit full boost.

I'd check everything out, I'm assuming you're using the On3 bov and wg? If so check the wg to make sure it's seated and the valve is moving free, and check the bov to make sure that's not leaking.

 

I dont have a on3 kit ,but from reading on the corral it seems like exhaust leaks are a pretty common occurence.I havent seen a kit on corral that didnt have some kind of leak.So my suggestion would be to check for leaks first before anything.

 

You definately need to check the flex pipes if they have been having problems with the ones in the on3 kits like posted above.