Blown GTA

Specs are 220/230 .510 .510 114LSA

Short block assembly is to begin shortly and given a choice between the 305 Comp and ZZ-9 which would you choose? Here's the buildup

*2-bolt main factory 1-piece seal block
*bored .030/ 3.750 Scat Crank turned .020
*5.7 GM condition rods w/ARP bolts
*TRW Flat Top Forged piston 9.5 comp 0n 74cc
Blueprinted/Balanced assembly with Cam installation

This buildup is still without any heads and supercharger less but here's what I'm shooting for:

CA Emission complaint ran on pump gas, daily driven, street crushing torque monster, track trailing twelve second five hundred horsepower* beast.

BTW, as a personal goal, I will not be happy until I see a Viper punch it and still see my taillights.


Parts that I think are needed to obtain goal:

190cc AFR 74cc heads
ATI Pro-Charger P600 self contained
(D-1SC too much boost=bye bye engine)

Here's what I have to put on it now:

Edelbrock lower/Superam Upper intake
DFI 2-bar map fuel and spark management system
24lbs SVO

Fill in the blanks would you or correct what I have.


*Not RWHP but rated flywheel as per manufacturer.

Willie

iTrader: (1)

Just a couple of comments.

First, I believe in order to remain emissions compliant, 220/230 duration is a bit high. I have heard that 220 is the maximum. I myself went with the Crane 2032 (214/220) and have had no problems with my yearly tailpipe sniffer test.

The ZZ-9 has about 4 degrees of overlap -- not good for a blown engine. Don't even consider this cam.

It is not true that the D1SC will produce too much boost. It can be pullied to produce as little as 8 psig boost. Mine initially came pullied to produce 10 psig. The fact remains that this unit will not have to work as hard as the P1SC to produce the same amount of boost -- thereby producing less heat.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://members.optushome.com/au/downunder1/rides/willie/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

Guido

I agree with Willie in that the D1SC would work just fine.

However, I DISagree about that cam. I think that it will work just fine. The fact that it has such a large amount of lobe speration means it will idle good and burn the mixture more complteley. I feel it will pass just fine.

Although you might talk to comp cams about it and see what they have to say.

Good luck!
Sounds like a good buildup! Just make sure you get the AFR190's with heat risers.

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-86 IROC
Vortech stuffed EFI 406 in progress
-=ICON Motorsports=-
Cluelessness: There are no stupid questions, but there are a lot of inquisitive idiots.

Willie

iTrader: (1)

Let me get into a little more specifics on the camshaft issue. Lobe separation angle does not tell the whole story. You must examine the valve timing events and calculate actual overlap -- the time both intake and exhaust valves are open. It is true that the ZZ-9 has about 4 degrees of overlap; this is not good. Talk to TPIS about this. I believe they will tell you exactly what I'm saying -- I inquired about this cam when I was considering it and was told it would not perform well under boost.

Also, never discount a cam solely on its LSA. The general rule of thumb for a blower cam is it must have >114 LSA. While this generally true, it is not always the case. The case in point is the cam I chose, the Crane 2032. It has a 112 LSA, but the valve timing concurs that it has absolutely zero overlap -- perfect for a blown application. Here are my real track results:

Best times:
Normally aspirated = 14.07
90-hp Nitrous = 12.58
Supercharged (6 psig) = 12.57
6 psig + 50-hp = 12.04

All I can say is do the homework on all the cams you're considering. Get all the specs from the cam card. This information will help you make an informed decision.

Willie

[This message has been edited by Willie (edited January 19, 2001).]