hey im no stranger to boost but i know none of the tricks and good parts when it comes to all motor building. looking for about 9500 rpm and 250 hp on an ls longblock. i know ill need the basics, internaly fuel all that stuff. does anyone have suggestions for specific parts i should use for this goal. also what should i sleeve the block to? thanks

 

You want to run a b18a/b @ 250hp?

You will need some (13:1CR) or so pistons and some lumpy cams right off the bat.
-complete rebuild on the engine with some serious parts that will combine well and make good power
-ARP rod/main studs
-Good map/tune


I'm sure the others will chime in...there was a thread earlier today about NA non-vtec B-series engines and some of the guys here have built/seen some badass setups

 

would i need a CR that high if i went out to like 86 mm? or is that unnecessary for a 250 hp street car? pretty much anything is a possible with this build as it is going to be done right with only the best parts, but like i said it is a street car and my goal IS only 250 hp so i really dont know how far i need to go, also what are some good brands to trust as far as internals and all?

 

Oh, I see, 250 hp at the crank, not whp that most everyone else uses, so that would be about 225 whp. Yes I remember a race set-up posted with ITB's that was close to that. It was stated to have 240 something, not sure if it was whp or hp at the crank. I believe the restrictive head will be the most difficult factor to overcome. Good luck and let us know.

 

Are you going to use a VTEC head or an LS head? With a VTEC head 250 to the crank is within reach. It may be possible with an LS head, but your cam choices will be more limited. It is going to be tough to get the LS head to flow enough air for that kind of power. I am currently building an LS motor with an 85mm bore , around 11.5:1 compression, and a ported LS head; if I break 200 Dynojet HP I will be satisfied.

 

wheredo you think that will land u in the quarter? and if i bore out an ls head (which i am planning on using) and get big cams and all the valve train work how will a vtec head still be better? if im flowing more cfm's than a vtec head which is easy to do, how is vtec beneficial?

 

you only want 250, thats kinda low...

there is no off the shelf non vtec cam that will make 250hp

there are several vtec cams that will

that and you will need to spin the engine to 9kish like you said you wanted to make that kinda power and frankly the LS rocker arms arent gonna like that

this is for a street car right? do you have any idea what a non vtec engine will run like if you do make 250hp? mines borderline streetable at 180hp

do some research before you come in blasting off HP figures...

 

Like someone told me earlier this week, having such a high rpm goal in an N/A setup is going to make your throttle a lightswitch. On and Off.
If I were you, I would consider your torque and HP goals as a balanced solution. You can get 250, but at what expense? Nill for power before 5K, and that I know with a VTEC head. I can only assume that a built non-vtec head hunting for high end HP is going to be like a VTEC killer head. Your streetability to going to be erased. Think about it, if the motor is setup to handle extremely high RPM, then your valve overlap is going to be huge. Cool for screaming down the drag strip, but when your light to light, and the engine is in low rpm, the overlap actually reduces power because too much overlap results inlow intake pressure and intake charge contamination because the high-pressure exhaust gases bleed into the low pressure intake. This will get you a lopey idle and a big loss in low end power.
Besides, if I told you you could make 300 hp@10,000 rom, and then told you I could give you that same 300HP@7,500rpm, which would you choose. I like my power early and long.
Best of luck, I know these all-motor setups are a completly new world from boosting. Much simpler though.

 

thank cushing and outtacontrol, i really havent done much research i figure i could prolly get some more definite answers and save time by going on here. but thanks for both of you guys inputs it really kinda opened up my eyes to what i will need to do before i even start my project, such as get a vtec head. what do you guys have to say about compression ratios and piston sizes?? thats another thing that i need to take into consideration as well as i could care less about keeping the ls motor its seeming like it would be easier to just go with a b20/vtec maybe? kuz then i got vtec and big bore....what do you think and cushing whats your 1/4 mile look like with 180 hp?

 

i didnt get my final tune done untill after the tracks closed.