i searched, but most of the results seemed to be boosted stock blocks, which is a little scary since stock compression is 10.3:1. so, im making my own thread, plus its late, ive been working out in the garage and im tired and want to sleep. easier to post this. anyway, a #4 valve is pretty much screwed so im either goin NA or single turbo. looking for advice on what to do for a RELIABLE autocross/street car, if i go turbo, plans would be:

8.5:1 compression
15lbs of boost (about)
target of 400hp
engine built to handle 600hp
conservative tuning

seems like turbo kits added to stock blocks put 8-9lbs on 10.3:1 compression, so maybe 15lbs on 8.5:1 would be conservative to start with.

thoughts?

 

basically im asking if that boost setup will be reliable and last 100k miles or if to get that reliability ill need to stick with a 270hp na build

 

Go NA mate for reliability. FI for power.

 

You wont need 15psi to make 400rwhp, more like 8-10 even with low compression

But read this thread https://my350z.com/forum/forced-indu...-worth-it.html

 

+1

At 400 whp, a properly built engine should hold up for a while. For that HP level, I would look at a twin turbo kit with small turbos for fast spoolup and a broad torque curve. GT25 turbos should be able to get you to 400 whp, and should spoolup very quick. For some headroom for more hp, you could go with GT28 turbos, but they won't spoolup as quick as the GT25s.

 

i already read that, but it doesnt talk much about what compression in that thread, which leads me to believe most where on stock compression. i wouldnt expect a 10.3:1 motor to last long on boost. 8.5:1 would be a different story, or thats what i was thinking anyway. so by the thread reference, im guessing you vote NA?

 

could i not achieve the quick spoolup and broad torque with a properly planned single turbo setup? from my limited turbo knowledge, i thought that was possible. a single will be much easier to build. i would be doing custom tubing for the turbo kit is i go that route.

 

Compression does not have all that much to do with reliability. You will find guys wit 4 cylinder Hondas boosting 25psi all day, with a 12:1 CR built motor.

Key word here being built.

Tuning is also crucial.

 

i would build it for 600, but shoot for 400. sounds like NA is the way to go for me

 

No, most boost builds are 8.5-9.0:1 Compression. But based on your goals i would say NA, maybe even high compression NA w/spray. If tuned properly that can be just as (if not more) reliable than boost, and ALOT cheaper.

 

build an NA beast man!! i love my NA beast...

 

You can't compare Honda builds to VQ builds, inline 4cyl and V6s are totally different worlds when it comes to tuning/boost.

 

na build isnt really cheaper than fi, with all the builds ive seen out there to achieve 320+ whp they seem to drop a good fair amount more than some one doing a bottom end build and a single or twin set up, maybe i am mistaken though but a full NA build seems to be more costly

 

and depending on your track you might want to be N/A anyways those long high rpm straightaways where your on it in 5th 6th seem to not fair to well on boosted vq's, like road Atlanta for example

 

NA builds can be done fairly reasonable, all i would really upgrade would be the pistons, rods, cams, springs. then bump the rev limit a tad. i would do the same with a turbo, but i would have the added cost of the turbo setup, plus a lot more work

 

I just bent a rod in my stock block, single turbo G35 Coupe… AND I’m still glad I went Forced Induction over a built Naturally Aspirated engine that still would’ve been running right now.

 

haha, funny you say that. spray is what lead to my messed up valve. ive got thousands of $ into my nit setup, utec, lc1, a/f reader, bottle heater, warmer, remote guage, opener, etc. but, i still melted a plug and part of it either damaged the valve or arcwelded itself to the valve so it wont seat. either say, if im building a nit engine, it will be less than 10.3:1 compression. and to be honest, i dont want to mess up a brand new engine so i decided to scrap the whole nit idea and sell the kit anyway. that way i could safely go up to 11:1 in compression. but then i was thinking because im an 4500ft elevation, a turbo makes a lot of sense, so here i am

 

idk what to do

 

i think u will regret NA build.. if ur prepared to drop the doe then i would go built and boosted.. look for built block by one of the vendors.. and u might want to upgrade a few more things then what you listed.. and if your tracking this u might want to moly coat internals aswell as a few cooling support mods.. your lookg at 15k but im sure your aware of that

 

LS2 Swap </thread>