Hi, I am building a 388 small block. I want to be able to run very low 12s and it seems that 400RWHP is the number to shoot for.
I purchased a comp cams nitrous cam part# 12-568-4 with lifters (anti pump up lifters part 858-16) and matching springs it is, 240/253 duration @.050 with 507/525 lift. Will that cam be streetable? My goal is to have a weekend driver, appear stockish but sound mean. What im asking is will I be able to make this idle well?

The other thing I was wondering was, if i dont run nitrous will this motor still be strong? And will I be able to run nitrous with a cast steel crank, hyper pistons cast connecting rods?
Any help is appriciated, Thanks,
Dennis

 

What compression?

 

I have GM 441 heads currently fully ported, but they are for leaded gas so i figured instead of getting them redone i would try to save up for some aluminum heads... I think with the 441 heads at 72cc i was looking at 9.7:1.

 

I will not be using the 441 heads, what compression is suggested and anyone have any answers to the above questions?

 

I'd go with the smaller version, the NX274... I was originally running an XE274 (230/236, on a 110LSA) and went 12.52 @ 108 on motor and 11.77 @ 115 on a conservative 100 shot. I switched to the NX274 (230/244, on 113LSA) and the results were pretty good. I only made it to the track once before I pulled the motor and it went 12.60 @ 107mph on motor and 11.62 @ 117mph ...Now, that doesn't seem like a big gain, right? Well, the car made so much more power that I couldn't hook it and lost .4 in the 60ft compared to the nitrous passes with the old cam! So it ran a faster time with an absolutely horrible 60ft.

 

What heads are you using? How did the first cam you have idle? Were you able to drive it on the street or was it strictly a track car?

 

The NX274 has a really nice mean/lopey sounding idle @ 800RPM. There was no hiding it whatsoever. The XE274 actually idled quite smooth... So smooth that I I've fooled quite a few people into thinking my car was much slower than it really was. "It's just an old Vortec truck motor, 12.80's all day on a 100 shot!"

I had unported GM iron Vortec heads. With 3.92 gear, 3500 stall, and a TH350 I'd get like 14mpg cruising around. Another thing I should stress is that I never once did any tuning to my old motor whatsoever... Set the timing at 32*, left my 750 Speed Demon untouched, and went racing. I left a lot of potential on the table.

 

This is good to know, I run a pretty similar setup as far as the vortecs, xe274, 750dp and was wondering about switching to the nx cam if i sprayed. sounds like it will be worth it especially with what it did with no tuning and a lost .4 in the 60ft.

 

how does the XE274 with its 110 LSA idle "smooth" compared to the NX 274 with 113? but that NX cam would be better with the vortecs anyway with the increased lift and duration on the exhaust...

 

240/253 duration @.050 with 507/525 lift

It seems as though the cam I have is a bit more extreme? Is this going to be a problem to get idling?
As for the heads, It looks as though I am trying to get The DART Iron Eagle 200CC intake ports with 72CC combustion chambers. Will these heads and cam go well together? Remember my aim is for 400RWHP from a 388... shouldnt be that hard

 

what will your CR be with the 72cc chambers

 

Comp describes it like this: An earlier exhaust opening and a longer duration make for a very pronounced performance sound. If you are looking for that Pro Street camshaft sound, the Nitrous HP™ cam is for you.

I can only explain it like a very rhythmic lopey idle - not too rough but no where near smooth and it's undeniably "bad" sounding to even the untrained ear.

 

i dont know maybe my grasp of cam specs isnt as good as i think it is but they still appear to be the same cam except for the exhaust valve timing which is a bit latter i can assume that is to help trap expanding gases in the chamber to utilize the N02 better and they had to move the intake valve open later but intake the ramp rates are the same so is the duration

but again the exhaust is a little more lazy on the XE with a little less duration
but the xe still has a 110 LSA

so it doesnt matter what comp say it will do in thier ad they are trying to justify buying a NX cam which is $10 more than the XE for some reason

i still say the XE will be more lopey than the NX