How many 347's out there
 

What kind of power/ET are you guys seeing with using the smaller 3.905" bore... I had planned on using an 6.0 block, but I came across a complete 5.3L for not much money, and was wondering if it would be worth it to bore it to 3.905 and put forged rods & pistons in it and an F1 ProCharger vs the 6.0 and procharger. Just wanted to see how much you can get out of these smaller bore motors.. It will cost me double to buy the 6.0 core engine.. I figured I could have all the machine work done to the 5.3 to be at the initial purchase price of the 6.0.. I know I could make alot more power with the larger bore 6.0, but if I could get between 700-800rwhp with the 5.3, thats all I need, and I can save a few bucks in the process. This is going into a 3,000# 68 Camaro, and an looking for 9's Please post up your combos ...Thanks

My car made 754rwhp with YSi, and 860rwhp with GT47-88 with 3.910 LS6 block.

I think 650-700rwhp with F1A is no problem.

well I went 9.8@141 with my 347 ls1 and D1 procahrger and my car weighs 3500lbs

Whats your build look like?? How much boost are you running to go 9.8x ?? Is your D1 maxed out??

according to his sig he was running at 13 psi

John,

What heads and how much boost were you running with the GT4788.

Thanks-

Zach

9.9:1 CR 243 heads with some mild clean up work, Vic JR intake, elbow with stock TB, Comp LSR blower cam, 60lb injectors and METH, about 13 psi. It was a 7.25/3.4 pulley combo.

That 9.8@141 was my second pass with the TH400 had a bearing failure in the blower about 2 weeks later never got to see what it could really do

^what was your fastest time with a stick dishmittie if you don't mind me asking?

Hmm well I went 10.0@139 @ 16 psi, and I made 86x rwhp at 24/25 psi. I wasn't really to run all out @ 16 psi as it was a license pass, but I think I could have run 9.8@141 since I didn't launch hard and only went a 1.55.

I went 9.40@143 mph with the blower setup, 680rwhp, 3450 raceweight.

What heads?

Very nice, using stock heads yet!...Why did you use the Vic Jr instead of a FAST or LS6 intake... just curious.. How big is the cam?

Best I went with the M6 was 10.3@139mph and that was with stock 241 heads, ls6 intake, and a smaller cam(230's for duration and under 600 lift).

Fast isn't worth the money spent on an FI build and the LS6 performs very well. I did the Vic Jr for the higher RPM power level.

The cam I was running when I went 9.8 was a 235/251 .624/.621 115 LSA

I went 9.47 @ 143 on my 347 with a T76 @ 16 psi a while back with a raceweight of around 3600 lbs. I still need to get it back out to the track again now that I have tried lightening it up a bit.

9.7's @ 146 in my thrown together in my garage shortblock

There was one that went high 8's with a D-1SC in a Trans Am. It has a TH400.

Thanks for the responses guys...I appreciate it... Now if you were in my shoes, which would you do?? I could buy the 5.3L for $350 and make a 347 out of it, or buy the 6.0 for $750 and either make a 370 or 408 out of it...Either engine I build will be Procharged....My goals are to build something that can push a 3000-3200lb 68 Camaro easily into the 9's on pump gas.

im a 347 but i aint finished yet.. building a twin 60mm precision turbo setup on mine. expecting 700whp on pump gas once finished :)

I would get the 6.0 and do a 370. That block has more potential for a bigger motor. Now if it was between an Aluminum 347 and a iron 370 I would do the 347 to save the weight of the front end

I'd run a 9:1 6.0-based setup.

I would go 347 but i might be a little bias. If i was going to use an f1 then i would go with the 6 litre block.