Two 95 talon tsi FWD's with similar mods, yet one pulls harder

[gregalmighty]

Okay I've been doing some research on something but need more suggestions. Here's the thing: I have 2 95 talon tsi FWD's with similar mods, yet one pulls way harder than the other. The weird part is the slower of the 2 has a 14b and the other still has the t25 which has been smoking bad lately.

Anyway info on the slower car: 145k on chassis, rebuilt 7 bolt with 20k, 14b, 3" turbo back exhaust, eBay cold air intake and cone filter, large fmic with short route piping, greddy type s bov, centerforce dual friction clutch, evo 9 fuel pump.

Info on other car: 126k original miles, t25, 3" turbo back, dejon tool intake with cone filter, smic with stock pipe and bov, act 2100 lb. clutch, fidanza flywheel.

Both cars have the bov recirculated and are running wastegate pressure, but the car with the t25 pulls way harder than the other. I've done a boost leak test on the car with the 14b, fixed all of the leaks and then checked again and everything was fine. Compression is right around 175 across the board as well.

I'm starting to think maybe the wastegate is not closing all the way, or else my clutch is slipping but its only got 20k on it and I've never launched hard or really done anything to abuse it. My e-brake doesn't work so I'm assuming a large enough block of wood in front of the tire will have the same effect to stop the car from moving while i check the clutch using the rev to 2k and dump the clutch in 5th gear method. Also wouldn't a boost leak test reveal the wastegate not closing all of the way?

Anyway, is there anything else that would cause that much of a difference between the 2? Does the car with the 14b and evo fuel pump just need a tune REALLY bad? I don't have a logger yet, so I've only been running the cars on wastegate pressure. Both cars have new timing belts and accessories but could timing be an issue here? Both run and idle fine and have no symptoms of timing being off.

If there is anything else you can think of here let me know, I will be checking the wastegate and clutch because thats all I can really think of off the top of my head. If I can give anymore info

 

[blownturbotsi]

Pulls harder how? Butt dyno or side by side?

 

[gregalmighty]

butt dyno, haha. Say rolling at 30 in 2nd gear I mash it until the top of 3rd, the car with t25 has instant spool up and throws me back in my seat pretty hard and will end up around 90mph while the other car takes a little longer to spool and doesn't have nearly the same feel once it is at full boost. Top of 3rd in that car I'm lucky to be around 80 mph. Side by side I'm sure the car with the t25 would walk the other one but I really don't trust any of my friends enough to find out haha.

 

[GSX93DSM]

I see a few things. One is the faster car has lower miles. Could have less wear and tear on the motor. Also every car is different. There might be that one car that runs fast as hell and you don't know why.. You never know how both cars were treated like in the past years.

 

[blownturbotsi]

Well it says that the 7 bolt was rebuilt and has 20k on it so that may or may not be the problem. Wastegate boost does vary on both turbos as well. 14b should do less than the t25. As far as one doing 90 and one doing 80 at the top of third, that doesn't make sense since they are both fwd 2g's and "should" have the same ratio gears.

See if you can get a friend or sibling to drive one and do a third gear pull side by side. Also get a logger!

 

[gregalmighty]

I know every car is a *little* different but this is very noticeable.

As far as one doing 90 and one doing 80 at the top of third, that doesn't make sense since they are both fwd 2g's and "should" have the same ratio gears.

That statement makes me lean more towards the clutch being the problem.

I'm set on dsmlink so I'm going to hold off on a logger until I get it and use that.

Thanks for the input, if you think of anything else let me know!

 

[Defiant]

butt dyno, haha. Say rolling at 30 in 2nd gear I mash it until the top of 3rd, the car with t25 has instant spool up and throws me back in my seat pretty hard and will end up around 90mph while the other car takes a little longer to spool and doesn't have nearly the same feel once it is at full boost.

You see why the T25 is used on so many street cars. It's very, very good for street use. It spools fast and boosts early. It will be out-run by a bigger turbo at higher revs, but for getting around traffic, the T25 is more than adequate.

 

[daren_p]

Do you have boost gauges on both cars, if so are we running the same amount of boost? The 14b's actuator should run with less boost, which may be part of the "lack of power". Do you have the BCS still hooked up on both or either car? Compression numbers & boost leaks tests are good on both cars correct? If you remove the WG actuator arm on both turbos, is some force required to extend the actuator abit to get it installed back on the flapper (ie some WG flapper pre-load)? Finally you may have to just run the side by side to be 100% sure ones much faster then the other. Because the T25's so small it spools fast & hits nice & "hard" where as the 14b will be slower & more linear. To some this may make the T25 feel much quicker, while it may not be the case.

 

[dsmsucks]

Me and a friend was in the same boat. Both cars were 1g fwds with the same mods. My car would put 3 cars on his on a third gear pull. We did a compression test and that explained why

 

[gregalmighty]

Yeah, the t25 definitely hits a lot sooner and I do have aftermarket boost gauges in both cars. The 14b climbs to 10 psi and sits there while the t25 spikes to 12 - 13 and tapers down to 10. Even at 5 psi on mild acceleration the difference is noticeable.

I have a larger turbo I plan on installing in place of the 14b so I know the fmic is a little impractical for the 14b right now but I also know that supporting mods come first.

The BCS is still hooked up on the car with the t25, on the other car its just got the lines plugged. Compression and boost leak tests were good on the car with the 14b, I haven't done either on the other car yet though. I'll check out the WG actuators today and see whats going on there. Another thought I had was maybe the evo 9 fuel pump is making the car run a little rich and thats part of the reason because the other car still has a stock fuel pump.

Anyway thanks again for the input !

 

[daren_p]

Sounds like there is probably a difference in boost between the two, making the T25 pull harder. The actuator on the 14b should run at a lower psi vs the T25 & then not running the BCS on the 14b will reduce it abit more. It is very common for boost gauges not to read exactly on, so for example, if the gauge on the 14b reads abit high while the one on the T25 reads abit low, the boost may appear to be closer between the two, then it actually is. Without the BCS hooked up on the 14b, I would think you would see more around the 8 psi mark.

At WOT I wouldn't think the evo pump would cause enough of an over run condition to make a huge difference, though it could be happening at low/part throttle conditions.

 

[gregalmighty]

That makes sense, the boost gauges are tapped at a different point on the intake manifold on both cars so I can definitely see them reading a little inaccurately. Thanks for the help guys, I will be posting back once I get dsmlink and get some logs because I'm sure I will need some help on those too!

 

[bane3d]

i read that the slower car have a big FMIC. Maybe it is too big for your turbo and you get some lag.

Agreed. I saw that too. I would want to know what boost both turbos are set at.

d

 

[rich3389]

When I used to have a 14b, my car felt slower than it did with the t25.
Most likely because of the lag though.

 

[gregalmighty]

Agreed. I saw that too. I would want to know what boost both turbos are set at.

d

Both running wastegate pressure as mentioned earlier.

When I used to have a 14b, my car felt slower than it did with the t25.
Most likely because of the lag though.

Did you do anything else to the car at the same time or was that the only difference once it felt slower?

 

[rich3389]

I just changed the turbo, although I cant say that I was boost leak free, because I had leaks, this was when I was a n00b. But I can say for regular driving the car felt slower because the 14b lagged alot more the the t25.

 

[kspharris]

Well for my nickels worth, I would check the timing belt on both to make sure that they are alignied properly and not a tooth off. I would also not describe the 14b as laggier than a t25 really, even though it technically is. The front mount, in my opinion, is not to big for a 14b. I run one. However for the boost you are running on both cars I would guess that the FMIC is one of the problems versus the SMIC. Also not having measured your piping length on both I would also guess that the FMIC length is longer. The fidanza helps alot on any setup with "pickup" or the butt dyno. So the combo of the fidanza on one car and the FMIC on the other may be the problem. I also know that the boost is and issue. You said it yourself, the 14b hits 10 and holds. The T25 spikes to 12-13 and then goes to 10. That is the issue there, I guess. Good luck with it. I would also consider keeping the 14b and putting the bigger turbo on the t25 car. The 14b can be a monster and 20 or so psi. Good luck.

 

[delta448]

The T25/SMIC is probably at a higher efficiency at about 10psi and below.
There is less exhaust energy spent in making the T25 spin.
The 14b is probably flapping the wastegate faster than the T25 in order to stay at 10psi.
A slipping clutch is a pretty serious disadvantage.

Turn the boost up to 16psi or more on both with a couple of MBCs and go run them again.

I'm wondering how the 14b would feel swapped onto the other car. ?

 

[gregalmighty]

Thanks again for the help guys! The clutch seemed okay from what I can tell that I thought may have been slipping. As for cranking the boost I'll try that once I get the logger. I had an mbc on the car with the 14b at one point in time but it took a dump and started leaking and caused a couple of ridiculous boost spikes which led me to taking it out, but from what I remember it felt like it started pulling pretty hard once it got past the 17psi mark. I plan on swapping the t25 out with the 14b when the time comes, the combination of things mentioned in this thread would account for the difference between the 2 I suppose - looks like I was thinking something was wrong when maybe there wasn't. Again thanks for all the help!