Spinmonster

A 402 longblock with a fixed 11.95 static compression that can't be changed at this point is completed. What cam recommendations would work well that gives a sane dynamic compression for use on the street with 93 octane in a 6 speed.

I asked this in the LS2 section with no resonses.

Thanks in advance.

slmdLS1

iTrader: (8)

ive always wondered what an f13 would do in a high compression 402. but i dont know the aspects that are important in picking a cam with that high of a compresion motor.

slow trap

iTrader: (22)

i'd say something like a 248/254 610-640 lift range should work well.what heads are you running ?

GuitsBoy

iTrader: (4)

running no or little cam advance will also bleed off DCR, but youll have to spin the engine higher.

beardWS6

iTrader: (1)

Im going with a 250 255 644 646 113lsa with 408 and ET 245 heads!

JakeFusion

iTrader: (7)

Comp XE-R 244/248 .612"/.615" 113+1.

That'll get you close to 8.5:1 DCR, and you can get close to 8.8:1 DCR on 93 with a spot on tune. If you go with much bigger of a cam, you'll need to tighten the LSA or have a lot of advance ground in to bring up the DCR and make very good torque. Either way, you don't have enough compression for any cam to make great average power and carry it much past 6500. More compression allows the use of a bigger cam that will peak much higher without giving up big midrange torque numbers.

If you've seen the longer thread in the dyno section on the 408, which I've responded to a few times, you'll know that a 248/254 needs something like a 12.75:1 SCR on a 114+0 to make great average power while still carrying the RPM range fairly high. Unfortunately, if you are using a FAST 90, you may not want to carry it past 6500, since that will be a major restriction on available power. Therefore, to maximize a 400cid engine, aim for around a 6200 peak and very good midrange power.

So, I suggest the Comp 244/248. The valve events will be good and it will make good torque and peak around ~6200. I've seen too many 402/408s that only pull 460-470rwtq and it's because the DCR is down around 7.8:1 or 8.0:1. Leaving 30-50rwtq on the table that a $100 flat mill could fix is just stupid after spending $10k on the engine. Also, make sure you are running a quench smaller than .040" or you are asking for trouble with compression that high.

RayZ06

iTrader: (1)

Jake Fusion has it right after talking with Comp Cams about my 408 project with Dart 225 heads they ground me a XE-R 242Int.248 Exh 612-615 on 112.Yank SS4000 will be a little higher in a 408 with lots of torque.Should hit the sweet spot.
Ray T