binder

iTrader: (8)

540 to 652.....way more than 50hp gain.

Borla worked great up to about 500hp then after that it was a no go. it's not a piping size problem since dual 2.25" has more cross sectional area than a single 3" exhaust. The problem is a single baffled muffler. I'm just clarifying that for others that think dual 2.25" isn't a big enough pipe.

binder

iTrader: (8)

Well there ya go. It sounds like everything is normal for this kit then which makes sense because there were a number of people on the gt35 wheel that barely broke 500hp even with methanol injection. MrPharmD is one of them. He put down more HP with his t-trim vortech. He was on the largest housing gt35r as well.

Also, don't worry about the dyno. Not only do dynos vary between each other (yes, even between 2 of the same type of dyno) there is a large variation of engines and cars. I have seen a swing of up to 10% power difference between the exact same race bike engines i've built with the exact same parts. Judging by dyno numbers i have seen on bone stock vehicles there is that same difference with car engines.

His dynos are posted a few posts above your post (page 9). Judging by his peak tq being around 5500 rpms i would say he's hitting full boost around 4500rpms give or take a few. I wouldn't see tq being delayed more than 1000 rpms after peak boost.

Personally, i think you are performing better than what you would with a gt35r.

SCHITZTANE

i thank you for the tip, but im not really concerned with what the ACUAL numbers are.we know where the problem is (down-pipe), i would be much more interested in how to fix this. seems i have no options available that appeal to me.

dont want to put in a cut-out, dont want to go full race with pipes protruding through the hood,cant go any bigger on the ar either.

SCHITZTANE

not sure i agree with u on this jeff.

if you look at gt35 mp kits WITH COMPAIRABLE ENGINE BUILDS the numbers are about the same as mine.

a good exmpl of this would be kparlit's g35. he made 540whp/527tq with a very similer engine build. the two maj differances are that he has a rev-up engine and he is tuned on 93oct.

btw his car is featured in this months issue of d-sport magazine, and he has been posting in the momentum kit owners thread.

with that being said i dont think im underperforming as much as i first thought.
my tuner thought i was going to top out at about 560whp befor he ran into bp issues. so if you factor that the gt37 is has much more lag, the smart $ stays with the gt35 imho.

str8dum1

iTrader: (11)

you measure backpressure pre-turbo at the manifold. post turbo numbers dont mean much unless you thought your exhaust was too small.

Boosted Performance

iTrader: (14)

Pre turbo, right at the T4 inlet flange, and yes post turbo don't mean anything unless (like you said) you think there is a restrictive muffler.


If you have a 3" downpipe, it will be good for a lot more power than what you are making. The 3" downpipe will flow a lot more than your Tial turbine housing (with a 2.25" inlet). Not sure what exhasut you have after the down pipe though.

BTW, back pressure is the exhasut gas pressure before the turbo, not after, as I see you may have the two confused a few posts up.

str8dum1

iTrader: (11)

are your 02 sensors pre-turbo then? thats where I was confused by your post about putting the BP sensor in the place of an O2 sensor.

Boosted Performance

iTrader: (14)

In the BP kit, yes, they are pre turbo. For test purposes I also welded the O2 bung just before the turbo inlet flange.

binder

iTrader: (8)

Numbers can be altered very easily on the dyno. The shop owner had the dyno set up funny that showed my car putting down 790hp on my first pull. I told him that it wasn't correct and he had to adjust some gear ratios that were set incorrectly to get it back to normal. He had it set up for a drag car before me and forgot to change it back. There was NO WAY of telling this on the dyno printout. I could have easily just used that and said my car put down that much but i knew it wasn't true. So if he can alter it like that then anyone can alter it.

The rpm pickup makes a huge difference as well. If it's not set up correctly it will read improperly. That's how i had him test that his settings were off. switched to speed based dyno run and it was back to normal so he then went in to check the settings on the dyno.

Of my personal friends high 400's on pump gas is all they were getting out of the gt35r wheel.

I personally believe there are quite a few dynos being posted that are inflated. Now, the person that had it done might not know so they say "no he didn't alter it" but how would they know the settings of the dyno? Maybe that shop owner wants all his customers to feel good so he alters the numbers to read high. It's hard to tell what some of the lesser known shops will do to get business. Especially if they are the ones doing these "amazing" engine builds.

There is also that guy that claims to have mid 600hp on e85 with a single walbro. That right there is impossible due to straight up amount of fuel flow so that dyno was heaviliy "corrected". A single walbro will barely flow 600hp with pump gas let alone e85.

so not a good thing to compare dynos.

If you have a 3" downpipe with completely dual exhaust that are straight through mufflers (no baffles) then i don't think exhaust pressure is the issue. Pre-turbo pressure would have to be the issue which means the exhaust cutout wouldn't fix that. Only way to fix that would be larger compressor housing.

SCHITZTANE

i am FULLY aware that differant dynos and engines dont give the same numbers! that is why i didnt base this opinion off of one build. i was able to find 4 or 5 mp gt35 kits with similer engine builds that i base my opinion on.

i just used kparlit as an example. do any of your friends have a similer build to mine? i bet not. i have jwtc2 cams,momentum headers,5/8" intake spacer, complete head work...oversized vaulves stiffer springs full port and polish, momentum dual exhaust, no cat converter, blahh blahh ect,ect.

SCHITZTANE

oh, thats interesting. the source of the problem ( according to my tuner) is that the headers didnt quite fit right causing the the downpipe issue.

let me see if i can get him to clear this all up. i dont like posting other peoples explainations as i usually get something wrong!

SCHITZTANE

looks like i had it all wrong! i thought they were saying that all my fitment issues caused thr back pressure. my back presure is preturbo(due to kit desighn) so since i cant get a bigger ar housing im stuck with the power i have now.

ty momentum for sticking it to me on that so called upgrade!

anyone who is thinking about a bigger turbo for this kit can thank me for being the ginny pig on finding its flow limitations!

Boosted Performance

iTrader: (14)

That is why I asked in post #8 about the turbine housing, and why I chose to use the much larger T4 housings instead of the T3 (Tial equivalent). I wish the T4's came in with housings larger than the .96 a/r, but then again, this is why we have the T4 twin scroll kit out for some experimenting. They go all the way up to a T4 1.32 a/r .

djamps

iTrader: (1)

Dynojets like most fixed-mass inertial dynos can't be adjusted. That's why they are practically industry standard. It's the load based dynos that vary so much (dd, mustang, ect)

For example I am within +/- 1 whp on two dynojets on the opposite side of town.

RudeG_v2.0

iTrader: (1)

Exactly.

binder

iTrader: (8)

explain how the dynojet that i get mine tuned on adjusts the ratios for the purpose built drag cars his shop builds?

Like i said, first pull showed i was just under 800hp and i knew that wasn't the case. It was the tach ratio or something he adjusted because it read completely normal under power verses speed. Power verses rpm made my car look like a completely monster. 800hp on 18psi with a 6765 turbo....ya right.

so if it can't be adjusted then this is the unicorn of dynojets.

binder

iTrader: (8)

that right there is the reason for the "lag" or late power band. Cams and porting on heads will always push the power band to the right which is the reason most don't do it until it's needed (over the 700hp range).

and yes, the person that barely broke 500hp is MrPharmD. He had cams with no head work on a gt35r with the largest housing offered. The poor performance after all the promises is exactly why he parted his car out last year.

So no, it's not new that all this hype is over rated. It's been discussed in great lengths and those that post info on it are usually flamed heavily by the fan boys of the top mount kits even though it's the truth. Read through some boosted performance threads on the matter.

Also, full engine build WITH heads was at injected performance (dynosty) and again barely broke 500hp. So far 2 reputable shops that have many high hp builds use these kits and they don't perform like the manufacturer claims. Red flag in my book.

SCHITZTANE

[QUOTE=binder;9653174]that right there is the reason for the "lag" or late power band. Cams and porting on heads will always push the power band to the right which is the reason most don't do it until it's needed (over the 700hp range).

and yes, the person that barely broke 500hp is MrPharmD. He had cams with no head work on a gt35r with the largest housing offered. The poor performance after all the promises is exactly why he parted his car out last year.

So no, it's not new that all this hype is over rated. It's been discussed in great lengths and those that post info on it are usually flamed heavily by the fan boys of the top mount kits even though it's the truth. Read through some boosted performance threads on the matter.

Also, full engine build WITH heads was at injected performance (dynosty) and again barely broke 500hp. So far 2 reputable shops that have many high hp builds use these kits and they don't perform like the manufacturer claims. Red flag in my book.[/QUOTE

well its obvious the kit wont do what momentum claims. i have a knack for getting burned on fi it seems1. midz350 im right there with u if ur reading this. lol.

seems i have more $ than brains. jeff, if bigger cams increase spool up, how does that push my powerband to the right?

binder

iTrader: (8)

Cams increase spool time. If it takes longer to spool then it's later in the power band.

rcdash

iTrader: (18)

Actually I think torque should be consistent on Dynojets. If the rpm pick up isn't working then the calculated hp reading can be all over the place. Speed vs torque can't be easily skewed. As you say, the horsepower curve can be because that is calculated from the rpm pickup.