393 street head

ef200098 · Aug 9, 2005

what head would you guys go with for the street? most people are going with the afr 225's. but i was also thinking of some victor's. would the victors be too much head for a street engine? what other head would you go with out of the box or with mild port work. This will be on a mild turbo 393.

mike

Joes95GT · Aug 9, 2005

I have a question first.

Do you mean the actual Victor head or a Vic. Jr.?

A Vic. Jr. is a bit too small for a 393, but will still work perfectly fine. I would choose the AFR 205 head over the 225 because the 225 has a much larger exhaust port - something that needs to be taken into consideration with a turbo build.

A Victor head will work on the car, no doubt about it, however, unless you'll be revving it to the moon, it wouldn't make a who lot of difference, and you'll save quite a bit, too.

Joe

Grn92LX · Aug 9, 2005

Try some 205ccTW heads from summit.

If your hell bent on afr's, i'd do the big bad 225's.

Victor jr heads are a nice head for a bargain, but a bit small for a 393. They'll work though. Its not like a turbo 393 is gonna be slow

If your putting this on a late model production 351 block, your already WAY past taxing it LOL.

ef200098 · Aug 9, 2005

its a 69 block and all forged internals converted to a 4 bolt main. and i am not talking about going with the victor jr's i want to know if the victor sr's will be a good head.

EDIT: what do the CNC'd TW'd flow? i know the 225's flow just about 300 at 600 lift. i think that will be about what im looking for to keep the 393 turbo streetable. that is why im going turbo afterall, to get big power and keep it streetable.

Don 95Vert · Aug 10, 2005

I have 205's on my Turbo 393. If you haven't done the engine already - don't do a 393, Not enough choice of pistons (1) for a forced induction setup to get low compression. The other problem with a 393 and a single turbo is the pressure ratio - the 393 puts out a TON of exhaust volume and you'll have poor performance if you don't deal with it correctly, with a balanced turbo and exhaust.

If I had mine to do over again, I'd do a 351 or 357 and get the CR even lower than mine now (8.9:1). The cubes you give up will be easily accounted for in a more turbo friendly setup.

Don

94GTLaserRC · Aug 10, 2005

Grn92LX said:
Try some 205ccTW heads from summit.

If your hell bent on afr's, i'd do the big bad 225's.

Victor jr heads are a nice head for a bargain, but a bit small for a 393. They'll work though. Its not like a turbo 393 is gonna be slow

If your putting this on a late model production 351 block, your already WAY past taxing it LOL.

A little :OT: but still an important issue: I noticed you keep suggesting the TW over the AFR's...is there any particular reason for that?

RC

ef200098 · Aug 10, 2005

Im going with a 393, but i will have a larger A/R exhause side for the added volume. i might go with a 91mm. i haven't really decided yet. Don, when do you start to see boost? and when do u hit full boost with that t-76?

mike

Don 95Vert · Aug 10, 2005

Boost is almost instant - I'd say by 3000 RPMs if I nail it, it'll go to max.

I have the largest exhaust housing available for mine and with a single 3" my P/R was 3:1 which is horrid. We had to go to a full 3.5" exhaust - which is quite a feat with a a stock K member. We also had to go to two wastegates both dumped to atmosphere to fix it. Higher boost will help but with a 91mm to get it in the sweet spot you'll have to run 17-20# of boost. With a High PR you know it because the engine hits a wall at a ceratain spot and just stops making power.

The 1/4 mile times posted are with the old MP T70 with a 3" exhaust and my old, inadequate fuel system at 12# of boost and getting out of it at the 1000' mark - haven't run it in this configuration, but it feels MUCH quicker. The dyno numbers posted are with the 3" exhaust and the 3:1 PR - it should be on the dyno in a week or two to get some new numbers.

I went with the T76 Q trim because they have better efficiency at lower boost levels than some of the other turbos. I suggest you get a compressor map for the turbo you want and just do the numbers - if it falls out iof efficiency range, than don't do it. I looked over all the popular turbo maps and the 76 Q was about the only one that had decent efficiency.

At those boost levels (17-20) pump gas will probably not be an option. If you zero deck the block then your CR goes up and it becomes more detonation prone - with AFR heads, like I said my CR with a non-zero decked block is 8.9:1. And If you don't zero deck the block, it will be more detonation prone. So with a 393 and a turbo you really can't win - the only piston you can use is a Probe -30 cc dish.

If I had it to do again, I'd go with a 351 or 357, zero deck the block and go with one of the MANY piston choices available to get an 8:1 CR. Mine is OK now at 14# of boost with water alcohol injection and a spot-on tune from the geniuses at LaSota Racing (LOL!!).

Just trying to keep someone from making the (expensive) mistakes I made.

Good Luck!!

Don

Grn92LX · Aug 10, 2005

94GTLaserRC said:
A little :OT: but still an important issue: I noticed you keep suggesting the TW over the AFR's...is there any particular reason for that?

RC

To try and get people thinking outside the norm and stop building a mirror image of what everyone else is doing. Instead of joining them, put a little thought into it and BEAT them by designing something better. I really like how you can buy cnc ported TFS TW heads now out of a summit calalog. Killer head IMO and it'll fit with stock pistons. What other 205cc head fits on a stock shortblock? If only I had more cash to throw into my car, the TW 185 or 205cc head would turn my 347 into a monster.

94GTLaserRC · Aug 10, 2005

Grn92LX said:
To try and get people thinking outside the norm and stop building a mirror image of what everyone else is doing. Instead of joining them, put a little thought into it and BEAT them by designing something better. I really like how you can buy cnc ported TFS TW heads now out of a summit calalog. Killer head IMO and it'll fit with stock pistons. What other 205cc head fits on a stock shortblock? If only I had more cash to throw into my car, the TW 185 or 205cc head would turn my 347 into a monster.

AWESOME, so the 185cc TW head is for the same app as the AFR 185?

Any differenc in flow numbers.? I may go ahaed with the the TW then when the time is right.

Thanks
RC

Grn92LX · Aug 10, 2005

The 185cc TW heads are bigger and flow better. I don't know enough about them, but i've seen guys with them and the numbers are killer. 86cobra on corral makes 371rwhp with 185cc TW heads on a n/a 306. It peaks under 6000 rpm.

See, I get ya thinking Not that afr's are bad, they sure aren't, but theres other ways to go fast(er).

94GTLaserRC · Aug 10, 2005

Grn92LX said:
The 185cc TW heads are bigger and flow better. I don't know enough about them, but i've seen guys with them and the numbers are killer. 86cobra on corral makes 371rwhp with 185cc TW heads on a n/a 306. It peaks under 6000 rpm.

See, I get ya thinking Not that afr's are bad, they sure aren't, but theres other ways to go fast(er).

In general, I think TW are the most under used heads/intake for what they are capable of. Never see any TW intakes around here, very few heads.

I talked to guys via email when I first started on here that used only TW stuff.

SOunds good.
RC

ef200098 · Aug 12, 2005

don, what size are your primaries for the headers?

Don 95Vert · Aug 12, 2005

1.75"

ef200098 · Aug 12, 2005

why do you think your PR is so high? i know most people aim for about 2:1. do you think the primary size has anything to do with it? what is the A/R ratio of your hot side? ive been reading compressor maps for about 3 years now so i know how to read them n such. do you know of a site has has a buch of compressor maps for larger turbos. most sites i go to have the t3 and t4's and at most a t76 or so. also if you run more boost on the 357 you are going to have the same exhaust volume as the 393 with lower boost.

mike

Don 95Vert · Aug 12, 2005

It's not that high now - it was though because of a combination of things. The 3" exhaust was too small, the wastegate recirculating into the exhaust didn't help and finally not running enough boost. Like I said, it was solved by a 3 1/2" exhaust adding another wastegate and dumping both to atmosphere and going from a T70 which has it's efficiency range at much higher boost to a T76 Q trim which is happy with lower boost levels.

Running more boost on some of the turbos WILL evacuate the gasses more quickly because they will be in their peak efficiency zone.

The primary size doesn't have much of an effect on pressure ratio, it's mainly what's AFTER the turbo that does.

stangbanger94 · Aug 12, 2005

I personally am running Trick Flow high port heads on my new 347 combo. The only thing that was bad was I had to spend the extra $ and buy Kooks, because no one else makes headers for those heads in a 94-95 GT. 1 7/8" primary tubing in 3" collectors is what I got the headers in. I think most people choose to go with the most common heads because of such issues, and the limited choices of headers to run with particular heads in a 94-95. I know it was a problem that I had, but I too didn't want to run what everyone else is. I would say if you are willing to spend the loot, go with High Port Trick Flows

Grn92LX · Aug 12, 2005

Whats your full combo stangbanger? Any numbers?

stangbanger94 · Aug 12, 2005

previously this combo made 465 rwhp n/a in an 89 notchback with a g-force 5spd, and 4:56's and ran 10.50's all day with out a 200 shot and 10.30's with a shot. The combo is as follows:
- CHP "Dominator" stroker kit (347)
-Sportsman block
-Comp cams custom ground flat tappet, Nitrous cam(of undisclosed duration )
-Trick Flow high port heads with Manley 2.08/1.94 ss race valves, Crower triple valve springs with titanium retainers,Harland Sharpe 1.6 adjustable roller rockers. Ports are fully ported and polished and gasket matched
-Edelbrock Victor Jr. carb intake fully ported and gasket matched as well
-Holley 750 double pumper carb(race prepped)

and it made that n/a power with 1 3/4" Mac headers, so the motor has now been freshened up, and will be breathing through way bigger tubing. It oughta be interesting to see what she'll put down now, and run in the 94.(she only ways 150lbs more then the notch)

Grn92LX · Aug 12, 2005

Nice combo man! This is an example of what happens when you think outside the norm of what everyone else does and do something way better. You make a TON more power.

393 street head

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