Low boost with High comp hybrid idea.

[keldore]

I am currently building an f22a4 NA as my DD. Im going to use bisi hbeam rods and bisi 10.5:1 pistons ( was going to do 12, but Jay at the local gofastparts shop Mr B's in rock hill sc said that would be too high for a DD) bisi stg 2 nitrous cam, f22a6 intake extrude honed/polished upper plenum, portmached and polished lower intake runners, maxbored TB, double stacked OEM style blacktrax iab plates (if I can I will have the working IAB plate as well so 3 plates total.. if It will fit). Getting head worked w/ valve job bisi springs, doing bowl shaping to keep air velocity at intake up (trying to keep the flattest torque curve I can). Megan racing header w/ custom 2.5" collector.

I just had a quick question about boost. Would this setup be ok to run a small amount of boost (4-8psi) or would it hinder the engines performance bc it is set up for NA. I just thought it might help to keep low end power w/ the higher compression, and boost to keep the high end power strong.. I know ill probably get flamed for this idea, but whatever. Another question is if the engine is left with that setup NA without any type of boost, would it be ok to run nitrous if so would I need to get better headbolts/studs to handle the extra cylinder pressure?
Thanks. Keldore (pics coming soon of the ole beater)

[David Lundin]

If you build the engine to handle the extra horsepower, and go with 10.5:1 compression I don't see why you shouldn't be able to boost, or do nitrous for that matter.

Before you do all this you should read up some more though, as you questions indicate that maybe you haven't yet acquired the knowledge that you need for such a build. Not trying to flame, but it can be really expensive in the long run to start doing heavy modifications before knowing how it all works together (not to mention you may be missing power from not matching things up properly).

If you really feel you want to build, I'd say find another good build and just copy all the parts, and make sure you have some good help putting it together (preferably someone who's worked on similar Honda engines before).

EDIT: How are you planning to do with the ECU? You will *NEED* to get this tuned properly after building of course, preferably on a dyno, so that's something you should take into account as well (dyno time isn't free for one, and you'll need an experienced tuner).

[keldore]

My p06 (stock) just came in today, I have a friend who said he could give me a hookup with a dyno chrome tune trading for some help swapping a 2jzgte into his sc300. You are right, I really dont know what im doing.. just trying to make a list and get to it so it doesnt not happen like all my other projects . Do you think my plan so far (without the boost) should work pretty well for getting a decently high, yet flat torque curve?

[David Lundin]

I honestly don't know enough about these engines to give a qualified answer. I say go to Bisimoto since you're considering buying from there. From what I've picked up during my short stay at the forum, they (he?) knows all you need to know about tuning these engines and I'm sure they'll help a potential customer get the right parts!

[AbsurdNY]

You need to decide on what you want to do. It is not a good idea to build a motor for NA and then decide to boost it down the road. Pick a choice and stay with that choice or you are going to run into a shitload of problems.

[deevergote]

NA pistons are generally of a high-silicon variety, whereas turbo pistons are usually of a low-silicon variety. The low-silicon pistons are the toughest, but they expand with heat. The high-silicon pistons don't really expand, but they can be brittle. With the added heat of boost, you may crack a piston designed for an NA application. A low-silicon piston may eventually wear out your cylinder walls when revving high due to the looser tolerances.

3 IAB plates/spacers won't fit without some custom work. You may need to raise the hood, or create a bulge or scoop. You may also need to extend your throttle cable, as well as vac and coolant lines. Be sure you understand what you're doing. Just because a double stack is known to make power, it doesn't necessarily mean that a triple stack will make more power... You CAN overdo things!


Honestly, David's advice to talk to Bisi would be the best advice given in this thread. Bisi knows about EVERYTHING. He doesn't race a turbo car, but he's probably far more knowledgeable about turbo than most of the boosted guys on this forum. He could tell you what parts would be best.

You CAN boost a high compression engine, and if you're only going 10.5:1, that's not at all an unsafe range. 12:1 would be pushing it... but even that can be boosted (I woudn't have a boosted street car with that compression, though... a NA street car with that is doable, however... but perhaps not very practical)

[d112crzy]

Whomever told you 12:1 is too high for DD is wrong. 12:1 is just fine, especially on a mild cam.

Also, 10.5:1 compression is hardly high compression. ITR's have 11:1 or higher I believe and people boost them all the time without issues, just as long as its tuned properly.

You can do whatever you want. Tuning is key. S2000's make over 600whp on stock internals.

As for running nitrous, go ahead and do it. Just make sure it's tuned and you've taken the proper precautions to run it. It's VERY fun, but can be even more dangerous than boost.

prNonVtec4u has 11:1 compression and has run a 140 shot without issues. He's planning on doing over 200 shot.

[deevergote]

Really? Holy crap, I didn't know he was doing that!

And yeah, nitrous can be very safe, or very dangerous... you need to understand and respect it, or the mad scientist and I are going to have to replace those piston rings you fried.

[chessboxer]

The longer the runners, the lower your maximum torque level is going to occur, if top end is your concern, remove the spacers altogether.

84000/Peak Torque RPM = Runner Length

There is a little more to it than that, but that honestly covers it for the most part.

If you want to do something crazy, adopt one of the variable length runner setups found on F1 cars. Talk about a crazy, advanced setup, but it means that nearly maximum efficiency/peak torque can occur throughout the power band.

Now, as for what you have said, you have NA pistons, a nitrous cam, and want to go turbo as well. My advice would be to pick 1, NA, NA/nitrous, or Turbo, and go with one of those routes, but I would not attempt to combine all 3. If the nitrous/na cam has a lot of overlap on the exhaust side, you end up pushing out a lot of your boost, and the scavenging effects that an NA cam/build needs are negated.

High CR does not mean that a car cannot be turbo, but it does mean that you operate with a lower margin of error when it comes to your tune.

If you really want the top end to be nice, I would focus on a nice and aggressive cam setup that the higher cr can take advantage of. You wouldn't have to have the add a turbo to the mix to get good top end.

For the first time in my life, I am not advocating turbo, god help me.

[d112crzy]

For the first time in my life, I am not advocating turbo, god help me.

Welcome to the awesome side.

[madwagon]

Welcome to the awesome side.

you mean my side view mirror? lol