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355 Vortec w/ X268 need more power
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RaG
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PostPosted: Wed Feb 11, 2004 8:52 pm    Post subject: 355 Vortec w/ X268 need more power Reply with quote

Track opens up on the 21st. Haven't ran my combo yet, but I feel the need for more power. I'm kicking mysekf in the ass for selling my 144 blower and going the high comp vortec route.

What can i do with my short block to make more power?
355
Studded 2 bolt main
factory forged crank .010
h beam rods 5.7
hypt flat top -6cc pistons
double key way balancer (anticipated small blower)

What should i do?
I figure some 210cc vortec fast burn heads would suck on the car since its a daily.

trying to figure in another 144 blower would mandiate new standard bolt pattern heads @ around 72-76cc, cam(but not a absolutely necessity) and the cost of the blower

any suggestions?

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96capriceMGR
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1996 Chevrolet Caprice

PostPosted: Wed Feb 11, 2004 9:40 pm    Post subject: Reply with quote

Are the heads 100% stock? If so some mild port work would definetely help.
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SMOKEmUP
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1979 Chevrolet Camaro

PostPosted: Wed Feb 11, 2004 11:34 pm    Post subject: Reply with quote

Take it to the track first and see what it does. Get a baseline first.

Make the car hook first. Did you put the converter in the car yet?

What accessories are you running? V-belts?

You always have the option of nitrous. I wouldn't run a plate system on that manifold.
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RaG
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PostPosted: Thu Feb 12, 2004 12:21 pm    Post subject: Reply with quote

Yea heads have no port work done.
I guess first things first, get it to the track and see how it goes.

I'm gonna save for 2 more weeks and ill have enough for a 200-4r and a 2200-2400 stall, may go a bit higher, however i have enough for a built th350 and stall now.

Running power steering, flex fan, water pump and alternator. w/ v belts

Yea i know the flex fan has got to go.

How high of a shot could i go with the HYPT pistons, i'm sure the rest of the bottom is strong enough.

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SMOKEmUP
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1979 Chevrolet Camaro

PostPosted: Thu Feb 12, 2004 12:37 pm    Post subject: Reply with quote

RaG wrote:
Yea heads have no port work done.
I guess first things first, get it to the track and see how it goes.
Wait on the port work for now. Get a baseline.

RaG wrote:
I'm gonna save for 2 more weeks and ill have enough for a 200-4r and a 2200-2400 stall, may go a bit higher, however i have enough for a built th350 and stall now.
Go with the 200-4r and a bigger stall, around 3000. The lock up converter will allow you to run a bigger stall and still be streetable.

RaG wrote:
Running power steering, flex fan, water pump and alternator. w/ v belts
Dump the flex fan! How big is the crank pulley? Can you run a smaller UD pulley and save some HP?

A serpentine drive might save you some HP. I got mine off an 89 firebird formula. But you'll have to swap the water pump.

RaG wrote:
How high of a shot could i go with the HYPT pistons, i'm sure the rest of the bottom is strong enough.
I wouldn't go over a 125 shot. Don't run a plate system on that manifold.
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RaG
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PostPosted: Thu Feb 12, 2004 4:14 pm    Post subject: Reply with quote

Sounds good for the stall/trans, thats definately next.

I'ma get a black magic fan to replace the flex fan. Stock pulley, don't know the diameter, ill have to measure it.

never really thought about an underdrive pulley

So if i decided to run nitrous and keep the RPM airgap vs a single plane, I would have to tap the intake runners (where bosses are) and spray through there?

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PostPosted: Thu Feb 12, 2004 5:42 pm    Post subject: Reply with quote

RaG wrote:
I'ma get a black magic fan to replace the flex fan. Stock pulley, don't know the diameter, ill have to measure it.
I've had better luck with factory stuff. You can pick up a dual fan set up for an LS1 for cheap money and you should be able to retrofit it into your car.

RaG wrote:
never really thought about an underdrive pulley
It works for all the new stuff. I'm not sure what diameter you have but you might be able to slow down the accessories a bit and make some power. I personally like the serpentine drive.

RaG wrote:
So if i decided to run nitrous and keep the RPM airgap vs a single plane, I would have to tap the intake runners (where bosses are) and spray through there?
Yes. You're asking for trouble with fuel / nitrous distribution on that manifold with a plate system. You might get one cylinder lean and go BOOM.
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osmiumfoot
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PostPosted: Thu Feb 12, 2004 9:28 pm    Post subject: Reply with quote

Smoke - when you say a plate system you're talking about a jetted plate, yes? I've read where some of the new spray-bar setups work well on a dual plane and RG wouldn't have to drill and tap. Is this an alternative?
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96capriceMGR
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PostPosted: Thu Feb 12, 2004 9:28 pm    Post subject: Reply with quote

I have never used nitrous but my understanding is that for a small shot you do not want individual port because the fuel jets get VERY small and easier to plug, plug one up and BANG, at least it makes sense to me.
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SMOKEmUP
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PostPosted: Fri Feb 13, 2004 12:17 am    Post subject: Reply with quote

osmiumfoot wrote:
Smoke - when you say a plate system you're talking about a jetted plate, yes? I've read where some of the new spray-bar setups work well on a dual plane and RG wouldn't have to drill and tap. Is this an alternative?
Yeah...I'm talking about the NOS plate system , powershot and super power shot type systems. I haven't heard of such systems. But I'll take your word for it. Based on the manifold design of a dual plane I don't think it's a good idea to run a plate system. How much space does the nitrous and fuel really have to mix evenly. I just wouldn't run that type of manifold with a plate system.
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355firebird
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PostPosted: Fri Feb 13, 2004 3:30 pm    Post subject: Reply with quote

I was told I could run a plate shot on my RPM air gap manifold. I was told the middle needs to be notched about 1/2 inch which it already is and a 1 inch spacer should be added to distribute the nitrous better.
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clay
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PostPosted: Fri Feb 13, 2004 8:59 pm    Post subject: Reply with quote

I don't think NOS makes this style of plate, but what about the dual spray bar system like the Gemini Twin. It would have one spray for each side of the plenum divider and should be better for distribution. I can't remember if Nitrous Works or Nitrous Express makes it though. I think their actual purpose is for a larger shot than a regular plate, but maybe it would solve the dual plane problem????? From what I understand and have read, the main problem with hyper pistons is the top ring placement. It is higher than a normal forged piston and sees more heat. If the ring gap is increased to compensate for this, I don't think you would have a piston problem with a 150 shot, but the hyper pistons might not be as tolerant to detonation, so be careful with the tuneup. As far as the small jets in a low horsepower fogger, I ran a system on a motorcycle for years (9 h.p./cyl.) and didn't have a problem, but 96capriceMGR is right, they are small holes. Clay
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RaG
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PostPosted: Fri Feb 13, 2004 11:47 pm    Post subject: Reply with quote

I think I will probably end up porting the heads or maybe trying the Fastburn 210cc heads or some AFR 195s

If i get the AFR 195s it would give me an ideal head for a 144 or 177 blower, but I don't think i dig waiting on my heads to be built.

Id think the Alum Fastburn Vortec Heads may be too large @ 210cc for my current 355 and rather mild 224/230 .477/.480 cam, since its a street car also

But i guess thats down the road a sec, I'm positive I'm getting a built 2004r and a 2800-3200 rpm 10" lockup stall, and swap that flex fan out for a electric fan. I just know I wanna a little quicker than around 13.5s. Trying to get a feel for what i'ma need to do.

Would just a built th350 or th400 be more suitable? I'm really getting into drag more. 3.73s are barable for my amount of driving, rarely need to take the expressway, just hate to limit the car, ya know?

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96capriceMGR
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PostPosted: Sat Feb 14, 2004 10:06 am    Post subject: Reply with quote

I would think that with the high stall you should run for that cam and the non-lockup of a TH350 or 400 combined with the 3.73 the daily comupe would be unpleasant. I have however heard of lockup TH350s don't know if they can be built to take abuse or if there are performance lockup converters for that tranny but might be worth a little investigation.

Some porting of the Vortecs and maybe some good valves should put you up into Fastburn flow numbers yet keep the small ports and valves to keep velocity good for daily driver duties. Looking into SI valves myself they seem like nice pieces without paying for a big name and marketing.
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Smokin71RSSS
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PostPosted: Mon Feb 16, 2004 3:56 am    Post subject: Reply with quote

That combo should be putting you well into the 13's. How does it feel when you get on it and where do you think it's lacking power? Is it sluggish in the low RPM's? Does it not pull at the top? It could be a minor problem that's holding you back. For sure that stock stall isn't helping. Also are you sure the secondaries are opening up all the way. It's a common problem with vac. secondary carbs. If you know anyone with a mech secondaries carb (preferably a Holley 650 DP) try putting it on and see if there's any difference.
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