HX35/SMIM/FP2 cams combo performance

[jjrock5]

This is the setup I'll be running in the coming couple of months. The turbo will have the BEP .55 A/R housing and the cams will be a straight drop in with stock gears. The sheet metal intake manifold will be a Street Magnus with a 1g throttle body. The engine will be a stock bottom end 7 bolt with a 2g head.

I know this turbo spools up quickly but it still is a larger turbo. Given this situation PLUS the larger cams PLUS the SMIM has me worried. Im almost inclined to say good bye to my low end power/torque. Any thoughts?

This 99 GSX is a daily driver and it will have all supporting mods for the turbo, well except the bottom end. Being a daily makes me believe that low end power will not be there anymore.

 

[DSM_PWR]

Why would you be worried about it?

Its not like you went to a q45 TB and drag manifold...

All you did is open up flow with the SMIM and add cams for help up top..

Its definelty not going to have the throttle response of a 14b but wont have the lag of a 42r either.. but you already knew that... right?

 

[jjrock5]

Given personal experience that large cams pretty much take low end torque and adding the larger turbo I was a little skeptical. I believe it's a valid argument.

 

[slowgsr]

what you have isn't considered a 'large' cam at all, you will be fine. If you want 'low end' power, get a diesel. I know what you mean with the low end, im just bugging.


with that small of an a/r its not going to be that laggy.

 

[dsm-onster]

Spool won't be that bad. My fp2x cams simiilar to the hks 272s, the spool was 20ish psy by about 3500rpms. This was on the stock intake manifold. The spool actually is reported as a little better with most SMIM manifolds. Infact, the back to back comparison of the jmf drag vs. race manfold showed the drag manifold increasing spool speed. Spool speed increases but lowend flow decreases because the resonance of the 1g intake manifold is taken away, from my take on the situation. In all you'll not really lose as much low end as I feel you're anticipating.

 

[jjrock5]

Ok I just did some serious searcjing on these cams. I actually have comp 101200s. Ppl are saying I can say good bye to any off boost response or anything below 3500 RPMs. Can anybody confirm? Im taking this statement as bad because Im so used to having some low end. Now Im considering trying to get 101100s or FP1s or even HKS 264s...

 

[dsm-onster]

101200s are fp2s . . . See my last post concernign fp2 cams

 

[jjrock5]

Yea I know they are the same. It seems it's a 50/50 as to what ppl say about loss of low end power. im going to go ahead and keep them for now. I just hope I dont turn this car into a completely 180* as I am adding A LOT of bolt ons in one shot.

http://www.dsmtuners.com/forums/hangout/345171-jjrock5-gsx-under-construction.html

 

[e85_4g63]

I think your making this a bigger deal then need be. I understand that this is your DD and all, but are you thinking that your NOT going to be able to pull out on a hill or what? 4 cylinders don't make power down low. Your getting to worried. You'll be fine. What clutch and motor mounts are in the car?

 

[jjrock5]

I'll be running stock new mounts all over and an ACT 2600 w/ street disk.

 

[dsm-onster]

I know the term streetability is greatly subject to personal interpretation. But my setup is very streetable. Yes I lost some low end grunt. But I did not lose power band width. I gained power up top. It just moed everything um a few hundred rpms. And game more peak power to boot. I don't step on it at 2500rpms expectig stock cam performance. I down shift a little more. Or I just simply stay in the gear a little higher in rpms. Before I was feeling the need to shift to the next gear at 6-6500rpms. But o It feels good and keeps giving the same returns or more staying with it to stock redline.

Really, it's more fun because the powerband is still just as broad but up higher where more power can be made. So shifting is a little different and worth it for the powergains the fp2s/hks272s provide over the fp1s/hks264s.

Did you see my logs of the h1c vs small 16g? I was seeing 2 more lb/min or about 25whp more power at 5K with 2psi lower boost and higher intake temps. The larger turbo was already making more torque at lower boost that early in the rev range. So Yea, I feel too that you're probably making more out of this than it really is.

 

[welfle18]

I will be in the same sort of situation, but ended up porting my head a little bit and went with the bigger cams because of the front wheel drive situation. I was hoping to move the power band up some so I am hoping not to have as many traction issues with the fwd. But I will be running the stock 2g IM and the DK 272 I think is what they are calling them nowadays.

 

[airmail96]

You could always get adjustable cam gears and mess with the exahst and intake cam seperatly to gain any low end that you may lose.

 

[jjrock5]

You could always get adjustable cam gears and mess with the exahst and intake cam seperatly to gain any low end that you may lose.

I was thinking this but not really educated on doing this and i heard you need dyno tme to gain anything. I may stick with stock gears as these cams are dropin.

 

[dsm-onster]

You don't need dyno time; you just need a logger. Tune for the best broadest airflow curve you like. If you have link you can use the hp/tq estimate to dial them in. The accuracy of the link hp/tq estimate may not be spot on, but then again so may dynos read so very differet across the board. And as well many times dynos do put a real world load on your motor like the actual weight of your car. Thus turbos spool later than actual in may dyno sessions. Getting back on the street the cams and tune may be ajusted for a later spool than what really will be going driving the car.

 

[welfle18]

Sorry if the question is dumb but how exactly do you dial in for airflow? I know that there are airflow sliders in link but how exactly do you know what you are shooting for? Is it more of a feel thing or are you basing it off the compressor map? To get them to idle right I know you have to adjust as well, are you adjusting to the amount of vacuum you are seeing or shooting for a particular #. This will all be new to me but I need to kindof get a base to what go from I guess.

 

[TSIMonsteR]

If you were an auto, I can see this being more of an issue off the line, but, all you have to do is shift down.

Lag is overrated, from my experience. I've ridden in several 35r cars, and the lag was perfectly acceptable for street use. Actually, a bigger turbo is more usable in a way, on the street compared to the smaller mitsu turbos we're used to.

A tdo5 turbo acts like this...

nothing, everything, everything, everything, nothing, nothing, nothing

35R is like this...

nothing, tiny bit, little bit, more, even more, everything, everything, everything.

So you're not hitting a wall with the larger turbo, but boost is still there, and usable. If you need more, just downshift.

PS. credit for the analogy goes to another member, .