S-trim 347 or high compression all engine 347?

Joe 5.0 · Oct 26, 2007

Just throwing this out there for discussion. I have a B50 block with 8.5:1 pistons that needs refreshening. I am about to tear it out, put in new bearings, de-glaze the cylinders, and put on a fresh set of heads. Then I'll turn up the boost and go for 10's.

OR, should I sell the s-trim, and get a new H/C package and new pistons and run like 11.5:1 compression and go for ~400rwhp all motor?

Both will be fast, and the s-trim combo will probably be faster in the 1/4, but which will be funner on the street and cause less headaches? I know above 500rwhp my block is in danger, and I really have no extra funds for a $2k block. I could mostly finance the switch to high compression by selling the blower.

Suggestions?

Should I keep the meth injection if I go n/a high compression?

5spd GT · Oct 26, 2007

The S-trim 347 will be faster for sure, set-up properly.

A high compression 347 would probably be a little safer on the block.

Pokageek · Oct 26, 2007

s-trim it!

#1 Then it will be STREETABLE (if that is important to you) AND trackable. Meaning you will have usable power across the RPM range with boost. To me, it is not fun hitting a dyno number unless I have great power thru and thru.
#2 High compression N/A will be less friendly and limit you later if you want more.
#3 You can always reuse the s-trim on the new build if and when you do blow it up one day!

My - o.

final5-0 · Oct 26, 2007

As has been said the blower option will make the most power

I'd have to say the NA option would give you less headaches

I think you could obtain 375rwhp give or take a few and have no
drivability issues with a sharp tune

Where I'd be running up a red flag is ...........

How high is ... high compression

I mean ... you don't wanna have to deal with race gas or the like

Grady

SuperStang83 · Oct 26, 2007

I vote to keep it supercharged as well. More streetable and if you go high compression and want to supercharge later your options are limited.

Joe 5.0 · Oct 27, 2007

Well how much is too much on this B50 block then? I am getting married this spring, so money is tight, so no budget for an aftermarket block.

I was thinking 11.5:1 compression would be feasible on pump gas + meth for a little cushion.

Stanger007 · Oct 27, 2007

I've gotta also say that keeping the S-trim would be a great idea to have amazing horsepower and keep the car very streetable. Get it tuned and all the hassles are done.

With the mods you propose and a decent tire, you will be in the 10s. I wouldn't take the B50 over 475-500 unless you've got a great tune and don't mind rolling the dice a little.

If you think the car is still too slow, swap on a different pulley.

Wes

fastgtfairlane · Oct 27, 2007

you could get away with 11.0 to 1 comp on pump gas with aluminum heads without a problem. theres a guy on corral with a 11 to 1 347 with victor jr heads that is running 10.70s motor all day long.

5spd GT · Oct 27, 2007

The camshaft is pretty key in running higher compression.

I have seen several stangers in the 130 mph trap speed with the B50 block.

I think, built properly, they can handle 550-600rwhp.

That is the only problem you have with a supercharger, if something goes wrong, there is not much room for error. Something could end up letting go

Pokageek · Oct 27, 2007

Just a side note, I have worried sometimes when you run real high compresaion..wht happens if you go to a gas station that doesn't keep close tolerances on their octane or mixes one with the other....if you are running 11 to 1 you may want some insurance on that 93 octane rating.

go-stang5.0 · Oct 28, 2007

I run a 10.78:1 compression ratio and I wouldent go any higher for pump gas. I also run stock timing for added safety. No pinging yet (except when my fuel filter gets really dirty and my fuel pressure drops at WOT instead of increasing )

fish254 · Oct 28, 2007

wow how long have u had the 347 supercharged that u need a rebuild??

Joe 5.0 · Oct 29, 2007

It was previously supercharged for 50k miles by the previous owner. I then put on the s-trim and lifted the head at the track and passed a bunch of coolant. It probably doesnt absolutely NEED a rebuild, but i have it torn apart so why not. I fully expect another 30-50k out of it again.

Redsnk95 · Oct 29, 2007

11:1 all motor setup would be very fun, turn some rpm.

RAD · Oct 29, 2007

Redsnk95 said:
11:1 all motor setup would be very fun, turn some rpm.

+1!

Sirone · Oct 30, 2007

I like the all mota idea!

Sirone · Oct 30, 2007

I soon plan on shooting for a 331 stroker and 11's in the 1/4 on motor.

Joe 5.0 · Oct 30, 2007

How streetable would a high compression 347 with a pretty agressive cam be? Would it be better to stay EFI or go carb? Couldnt I run spray with the high compression if it wasnt fast enough?

BlackVert · Oct 30, 2007

i like the all motor thing too, but for a totally streetable combo with killer power in the high rpms, it is hard to argue with a low compression engine with a centrigual blower or a turbo.

just puttering through the neighborhood at 2000 rpms, the boost isn't there, so it can be just like stock, but the more you wind it up, the power just keeps building.

the other thing about lower compression is that it makes it possible to use lower octane fuel and save on the high fuel cost if you don't have the blower on or decide to make a concerted effort to keep rpms down and stay out of the boost.

and you can still make great power with a low compression motor, even n/a ... just look at KillerCanary's combo.

i got gun shy with boost because of the problems i had with my kb, which ended up killing my motor.

if i were you, knowing what i know now, i'd keep the 8.5:1 and the blower. i'd just be damn sure i didn't have any vacuum leaks.

final5-0 · Oct 30, 2007

I just don't see a drivability prob with a stroker
unless
You went very radial with cam specs

Since you have already defined the application as street

No need to go all out with some full race kinda combo as I see it

Grady

S-trim 347 or high compression all engine 347?

Joe 5.0

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