Can you go "Too Big" with a SMIM?

[rampridersrider]

After doing some research on intake manifolds and efficiency vs rpms I've come to a cross roads. Can I go to big with an intake manifold?

I'm currently putting together my car for this season. Just a simple stock 6 bolt bottom end, stock head with BC valvetrain and 280's, HX35, and all the supporting mods. With that in mind, I play on sticking with a stock bottom end for now so I want to make my setup as efficient and knock resistant as possible. Better effiency means easier, cleaner, safer power.

Now I had planned to rev the car out to 8.5k-8.7k, BUT I may stick to something like 8K depending on if the stock bottom end and trans doesn't like higher rpms. Which, while I'm on the subject, are 280's overdoing it? Or should I stick with a more simpler 272 setup? I want a strong powerband

Anyway, I've come across some good deals on intake mani's and before I drop the bomb I wanna make sure I'm not wasting unnecessary moola.

I can't decide on what I like more. I love the look of an AMS VSR manifold or JMF Drag manifold and have come across good deals on them both, but are they to much for me and would ultimately hurt performance? A local shop has an intake manifold that was custom built by a guy with the last name Schwitzer (I think), supposed to be the top dog in custom manifold building. I have to say its the biggest IM I've seen for a DSM and looks SICK. Huge plenum, with single piece cnc runners, Q45 flange, and an angled throttle body flanged so you can run a large 3 inch piping and not have to worry about relocating the battery. I can get a good deal on this intake, but with it being similar size to a "Drag" mani or VSR, would it be to much? Will I be happier with a simple JMF Street mani, or race mani? Or what about the Forrester manifold, it appears to have a smaller plenum though over the JMF street version, but I can't really tell.

Basically, is to big to much?

 

[Rob10_99]

I could make you one that uses a keg for the plenum. Yeah thats too big.
If your lookin to keep rpm's at less than 8k, I'd suggest going with 264's as they have more lift/duration than stock, but dont move the powerband up hugely into the sky.
But still, with the HX35 your going to be making power up top either way. How fast do you want it is the real question in picking mods.
I would get those 264's first off, and see how everything works together and get it tuned.

 

[dsm-onster]

280s will actually lower the resonant rpm of the runners because of the later effective close angle. See Induction Systems. I think 280s would be a good option for the hx35 with a larger turbine housing, like the stock 12cm^2 turbine housing with a non-divided t3 manifold, or the t3 .70 a/r bep housing. You'd do well with the 7blade 60lb/min hx35 compressor. But you would definately extract the most from the 52lb/min 8blade hx35 compressor. Yes, it really depends on your goal.

Here's what the VERY large JMF drag manifold did vs. the JMF race manifold. JMF Drag vs. Race manifold dyno.

 

[rampridersrider]

Thanks monster, I was hoping SOMEBODY would shed a little light for me. I've been getting mixed views on a lot of things. Lot of people tell me to just go with 272's and stick with the 1g IM, the guy above you just told me to get 264's and go from there, some just say go with a JMF street/race manifold. I'm actually looking for educated responses about whether it will actually hurt performance to go with a large SMIM. I would rather not buy twice or three times. I could care less if a 1g manifold has been pushed to 500+ whp or stock cams have seen 130 mph traps. I'm not interested in running 35 psi and 24* of timing to try and milk as much power as possible. I'm running a stock bottom end so having an efficient setup is crucial and having as little cylinder pressure as possible with the coolest intake charge.

I did see the Drag vs Race manifold test and the results were actually very pleasing. From the beginning of spool up the Drag mani was making more power than the Race manifold. Even though peak power they only seen a 16 hp increase, the power under the curve was amazing, as much as a 40 hp increase was seen between 5.5k-6k rpm, and the car had 35 more peak torque.

Jake Montgomery put the Drag intake on his stock 16g Evo and also saw large gains, but never saw a dyno. He mentioned that he used to spike to 28 psi and then settle to 19 psi, and then with the Drag mani it would only spike to 25 psi and hold 21 psi, possibly meaning that the stock IM was a choker, filled with boost extremely fast and then couldn't feed the engine fast enough and was losing boost, making the turbo work even harder to make more boost. Just a theory though.

 

[dsm-onster]

It would be to your benefit to get a set of adjustable cam gears with the 280s. They don't come out of the box exactly straight up. When you do get them dialed in and if you don't mind a bit of lope, some intake can advance *should* help your mid range a bit. But it really comes down to your setup and you'll probably have to monkey with them a bit to get the most out of them. I tell most people that it seams like our motors need more and more fine tuning the higher and higher in duration we go with a cam selection.

 

[need2boostpsi]

from that graph it seems that the "drag" manifold does a minimally better job at low end as well. so besides price why would someone buy the race version?

 

[turboglenn]

from that graph it seems that the "drag" manifold does a minimally better job at low end as well. so besides price why would someone buy the race version?

To extract every last ounce of top end power you can get. A race motor (drag or road race) hardly ever sees below 4000RPM and is usually kept in it's power-band as much as possible so the losses in bottom end wouldn't make any difference on the track. But they did get a decent torque gain of near 45lb/ft and a rather steady jump of 15hp, i could see it giving you the edge you'd need to dqueeze out the next guy if it came down to a "back straight battle" of shear power.

Someday a SMIM will find it's way onto my car, but i've been just way too broke to buy stuff i need, let alone toys (but i do love them toys )

 

[94Jettameowpsst]

If you run a t25 and a JMF Drag intake...that might do you in >.>

 

[Black_Bullet]

I think you can go with better cams than the bc280s honestly.
Im coming from BC272s and I am now selling them for a better cam selection.
Your going to spend just as much or actually more buying cam gears for the BC's and trying to deg them properly, especially if you need dyno time to set them up right as far as power band. Dont get me wrong, they're a great cam for the budget racer, and they do give results over stock cams, they did for me on my 16g setup, but they certainly aren't cream of the crop. If you want really nice cams look into Kelford cams ( what Im planning to go with ) or FP or GSC cams.

With the Hx35 I wouldnt worry about going to big on the intake mani with the options you've spoke of.
A JMF race or drag intake mani would make great results for you, especially if your not worried about moot rpms if this is more of a race car (i.e. under 5k ) were you wont really use in a race/ track run anyway. Figure your awd so you launch above 5k, with this setup probably shift a little above 8k, and w/ fast good shifting, rpms dont fall any lower than 5500, get my drift. Plus the holset turbos spool plenty fast anyways..I honestly couldnt tell you about the Switzer intake mani, It looks good though. Whats retail price on it?

At least seems like your doing your research and you have a understanding of tuning and efficiency.
Yes find a setup that you can flow as much lbs/per min at the lowest boost possible while making good cylinder pressure without needing excess timing. This generally will also net you good results on pump gas, but if your running meth/ e85 /race gas then most of that doesnt matter as much as you will be able to safely squeeze an intense tune out regardless with good fuel...

 

[e85_4g63]

If you run a t25 and a JMF Drag intake...that might do you in >.>

That's thinking with your dipstick Jimmy!

 

[rampridersrider]

Well my setup has changed since I posted this last. A local friend sold me his wiseco/eagle built bottom end for () $350. I picked up some 1600's and am going to run straight E85. I still have to pick up a new clutch as I worked mine over last season. Once I get in the new longblock and clutch this month I will pick up an intake manifold next. I really want that Switzer manifold although it is flanged for a q45 throttle body. I think if I pick it up I will have my local shop weld a 1g throttle body flange on it instead. I changed my mind on the cams. I've grown to dislike the BC cams. I'm looking into some FP2's/101200's right now.


What clutch combo did you end up going with Bullet?

 

[Black_Bullet]

Well my setup has changed since I posted this last. A local friend sold me his wiseco/eagle built bottom end for () $350. I picked up some 1600's and am going to run straight E85. I still have to pick up a new clutch as I worked mine over last season. Once I get in the new longblock and clutch this month I will pick up an intake manifold next. I really want that Switzer manifold although it is flanged for a q45 throttle body. I think if I pick it up I will have my local shop weld a 1g throttle body flange on it instead. I changed my mind on the cams. I've grown to dislike the BC cams. I'm looking into some FP2's/101200's right now.


What clutch combo did you end up going with Bullet?

I agree with you on the BC cams. Fp2s are better, my friend had those. I liked what I saw with the 75mm FFtec personally..
Have you ever considered going to a Hawver intake manifold?