First of all, if you want to run a SMIC, don't buy a GT 35/40. Apparently, there is no filter that will fit between the turbo and the IC. I talked to Sean today at A-Spec, and he was no help. KDR rigged up a "Home Depot" adapter with a 5" K&N filter in my installation. Trouble is, the adapter uses 3" pipe. The intake on the turbo is 4", so this setup decreases the intake area by +/- 40%. This would go a long way towards explaining my 300 HP vs. the 400HP numbers reported by those using a FMIC. A call to the "Tech" department at K&N was even more disappointing, as they do not understand that the displacement of a rotary engine is not the same as a piston engine.
Gathering whatever useful info I could from this "tech" expert, I don't think even my 5" cone K&N filter is adequate for this turbo. Has anyone ever calculated what size filter is needed for a turbo of this size? Is a cfm number available for big turbos? So much for buying a new kit. Wish I'd gone with something less experimental. (Gordon, you were right)

 

i still dont think that a 100rwhp discrepancy is due to filter sizing. take at look at the facts. you are the only one i know that has the GT3540 with the .82a/r. those that have dynoed around 400rwhp with ported and non ported motors are running the 1.06a/r.

anyone else wanna chime in on this?

 

I acknowledge that most people on this board are more experienced than I. Please explain to me how the a/r
(a being the 4" intake) is unaffected by the 3" intake pipe connected to it. Doesn't the intake pipe of 3" effectively change the a/r ?

 

Yes it does the intake size discrepancy will affect airflow to a certain extent, but not to the point of 100rwhp.

as far as the turbine sizing goes, if you ask around, most people will tell you to run a 1.00a/r or bigger on a TO4 based turbo. Being that the GT3540 is a T3/T4, you would need something greater than a 1.00 a/r.

I myself dont know too much about a/r's and such, but a .82a/r on a t3/t4 dual bb turbo is overkill. im sure it helps on spool time, but it will not let you get the higher peak HP. the 1.06 a/r is the optimal housing for the gt3540 .. look at toy, silver93tt, and my results from it.

 

while rallimike has a .82 turbine housing...his 100hp difference at 14-15psi than others with the 1.06 housing has to be due to other cirumstances..im sure that the gt35/40 turbo is not limited to the 250hp(?) # that rallimike dynoed... i think rallimike stated he still has the main/high flow cat still in..his car is probably not properly tuned or his engine is not to healthy...i think rallimike should do a compression test on his motor and then dyno it again watching the UEGO readings carefully

 

I am almost quite sure that his car was tuned properly by KDR. Also, I think that he has a new street ported motor done by KDR.

I know that he is running a setup that is noncoventional to the setup most single turbo FD's run (cat, 1200s, smic, etc). I guess I'm wrong, but I still think the .82 a/r plays a big role in the HP difference.

 

i agree the .82 will affect some top end power and give you some spool up time as a trade off but rallimike is only doing 250hp(?) thats rather low..it just seems like theres a different issue going on with his car

 

a clogged cat might, and would be the answer. putting in a midpipe might just wake that turbo up.

also, i think with the smic, intake temps are a major issue.

 

K&N Prt# RU-2510

4" inlet 3.5" filter length with .625" flange length.

I'm sure Dave can get that for you.

Since I never got the measured distance between the bottom of your IC and the inlet flange on the turbo, that's all I can suggest.

Thanks,Sean

 

The cat was replaced, first with a resonated midpipe, then a high flow cat. (Dave dynoed both, and the difference was negligible). The car now registers 304 HP. The only K&N filter that will fit is 3 1/2" long. K&N says that filter flows 320 cf/m. While I'm not sure what I need, I know it is more than that.
So, to get to the point, has anyone calculated the proper size for a filter? Anyone know the cf/m range of a single like the 35/40 ?
Once I know how big the filter needs to be, I can work on having a 4" pipe made to fit.

 

I'd have to agree with Poweraxel.
The A/R of the turbine housing will probably limit your top end, but it shouldn't limit you to 300rwhp.

Opening up your exhaust should make a difference (done with my friend's FC and my own Haltech driven FC and both used a 60-1 T04 with turbine A/R > 1.10).

How new is your engine? What kind of A/F ratios are you running on the dyno? What kind of intake temperatures are you seeing?

J

 

 

Brand new reman. Don't know a/f, but Dave said the lamdas were perfect ? PFC shows 46-48 in normal driving, which will go into the 52-55 range after a run to 100mph. They were in the high 60s when it was dynoed.
My goal has been a responsive, reliable 350-375 HP, which is why the .82 a/r. I think I'll get there, but it certainly hasn't been 'plug and play'

 

are we talking about an intake limiting your rwhp? if so run it without one on the dyno, if it is a huge difference than thats your problem, if not look else where.

excuse me if i am totally wrong on this subject i'm just learning.

luigi

 

luigi - nope, that is a good suggestion for determining if it is an intake restriction or something else!

 

AJatx
Very nice. Make, model, serial #, source?

 

That looks like an HKS intake with a 45 degree bend connector piece, thingy-ma-jig.

http://66.216.67.51/subcatmfgprod.asp?0=214&1=319&2=-1

k

 

For the filter issue for your gt3540, just clamp a screen over the inlet. having a aftermarket filter will not help bring the hp#s up. what you need to do is get rid of your cat and throw a midpipe on and that will open up your exhaust!!!! It just doesn't make any sence having 1200cc injectors, cat, and a single turbo?? also having a .82 A/R compare to the 1.06 A/R have alot to do with it too.

good luck

 

steve, I would love to go with a screen solution like you suggest, what pitch screen should I consider. Is screen even measured in pitch?!?

I assume something much smaller than screen door...will stop by lowes or home depo and poke around tonight...how about one of my old ladies panty hose sections? oh wait fishnet won't work... (gawd I hope she never reads this forum!!!)

K

 

you could go to ACE hardware or even home depot will have it. the screen that i have on my gt35/40 i bought it at ACE hardware and the pitch on it is small enough that no little rocks could get through but enough air will go through. that's the J-spec style.

 

jspec style all the way baby!!

I imagine it's pretty cool being able to see the compressor wheel spinning...

K

 

I suggest removing the cat before putting a screen over your inlet.

The big disadvantage with a screen over the inlet is that you'll be using all the hot air in the engine bay.

Just a thought

J

 

Watch out that the panty hose doesn't get sucked into the turbo -- that would be a big mess (melted nylon everywhere).

You can get Santoprene hose from McMaster-Carr to relocate the air filter. It is cheap and it works great. I have used it on my stock turbos and now on my RX6 to relocate the filter to avoid interference with my SMIC.

It comes in standard and metric sizes. The RX6 is 90mm, and it sounds like you need 4". Measure carefully before ordering. Go here (http://www.mcmaster.com/) and lookup part # 53145K67. It is $5.43 a foot with a 5 foot minimum. Get a very short 4" diameter pipe to attach the end of the hose to the filter.

-Max

 

Hi All
It has been interesting reading the story of the .82 and 1.06 hot sides. I recently got my car back from having the GT3540 fitted. As I wanted 350-400rwhp and don't want to boost beyond 15psi and wanted fast spool up, I went with the .82. Having previously ran with a PFS set-up I have a fair idea of what 300 hp feels like. Even getting used to the car and only running 10psi at present this is quicker. I think the .82 will only affect things at the top end. Don't forget this turbo is capable of 25+ psi. I think at 15 psi you will not be down 100 hp. There is a problem elsewhere. Intake restriction, IC cooling, exhaust etc.
I look forward to tuning my car and seeing the dyno figures.
Martin

 

On a side line. What EGT's are people seeing with the GT3540. How far from the turbo have you mounted sensors for EGT and A/F metres.