Well i did some research and came up w/ a few things. For one I will be going w/ a TRW forged piston meant for blowers, that should give me 8.1:1 compression. I will either mill the heads or block and/or go w/ thinner head gaskets in order to raise the compression to around 8.5:1. I will be getting the block o-ringed, to handle the 15lbs of boost it will see atthe track. I will use 10lbs on the street. The heads will be checked out and the rest of the parts that I will reuse like the crank will also be magnafluxed or whatever the hell they call it. Anyway, the important part is the camshaft selection. I will be likely using a custom hydrolic grind, and NOT getting a roller cam, so i can keep my costs down. I have a guy who'll grind a cam for about $225, and it'll work fine, since I'm using a blower and it's not NA. That way I don't have to getnew lifters and whatnot. The cam has been narrowed down to 2 choices. Because I wat to try and remain emissions legal and don't want to modify my heads to accept more lift, I will try to pick from these 2 grinds:

222int/230exh @.050 duration
510/510 in. lift
114 centerline
power between 1,800 and 5,100-5,200rpms
OR
215int/220exh @.050 duration
500/510 in. lift
114 centerline
power between 1,600 and 5,200rpms
(LPE superam w/ blower grind)

The engine will be run on pump gas on the street under 10lbs and race gas under 15lbs boost at the track.
I am guessing that this could net me 575-600hp at the track, when all is said and done. Roughly 500+ on the street. I hope. Either way, I'd like to be in e 11's. Does anybody have any suggestions on which grind might work better considering my parts and my goals. Thanks. -Justin



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SUPERCHARGED 87 GTA: Blk/Gld w/Superam, 355cid Trickflows, forged pistons 9.5:1. Auto 2,600 stall, 3.45 9 bolt disc, Best ET (Nat. Asp.): 13.567 @ 101.900 w/ a poor 60ft. Best mph: 104.3 -*100% NYS emissions legal*
http:// www.community.webtv.net/munks87/JustinsGTApage.com
VORTECH S-TRIM completed 7/9/01: 10 & 15 LB. Pulleys, HKS race bypass, serpentine swap. No ET: 8/26/01, Blew motor before track. Rebuild in progess. Beat a freinds 12.9 @ 108 Camaro by A LOT. EST. mid-low 12's as it was. Looking for 11's w/ new motor.

[This message has been edited by Justin 87 GTA (edited October 22, 2001).]

 

Hey I have a similar grind in my car, except it is a hydrolic rollor. See my sig. SLP 51006 cam or 51004(one is a rollor the other one is not).I forgot which is which. With 1.6 rockers total lift is .500/.520.

I'm running 12lbs with Felpro head gaskets. I think o-ringing the heads is over doing it. Usually GN's running 25lbs of boost get that done.

I'm also running a 9.8:1 compression. 8.5:1 is kind of low for the street. Unless you expect to up the boost to 16-17lbs. I thought mine was too high, but it doesn't knock and has great throttle response.

------------------
'91 Formula
383CI Superram, Sportman II's
SLP Cam 214/224 .470/.490
Vortech V1 S-Trim
5-speed
3.42
12.34@117.04, 1.91 60Ft.
on Drag Radials

[This message has been edited by '91 Formula (edited October 23, 2001).]

 

I agree. 8.5 is pretty low. You could keep your detonation back with just a couple degrees of timing I think and adding unleaded race gas for the track.

I have mine at 9.2:1 roughly and I ran 9psi this year (when the belt wasnt slipping). I plan on running 14 or so with the turbo next season.

------------------
-86 IROC

-=ICON Motorsports=-

 

Hmmn, that's good info thanks. When I spoke to a few engine builders, that's what they suggested, around 8.5:1. I'm underthe impressionthat the car would make more power w/ lower copression and the same total boost. Correct me if I am wrong. In other words a car w/ 11.5:1 compression and compression totaling 17 lbs total under boost, would make much less power than a car w/ 8.1:1 compresion, w/ compression totaling 17:1 under boost. Alos, that the 355, will make more power than the 383 under boost, for example. The blowers for somereason work better w/ smaller displacement. Am I accurate w/ this. Also what pistons areyou guys running, the ones I wanted to use are for blowers, and the rings are seated lower than normal pistons. thanks

------------------
SUPERCHARGED 87 GTA: Blk/Gld w/Superam, 355cid Trickflows, forged pistons 9.5:1. Auto 2,600 stall, 3.45 9 bolt disc, Best ET (Nat. Asp.): 13.567 @ 101.900 w/ a poor 60ft. Best mph: 104.3 -*100% NYS emissions legal*
http:// www.community.webtv.net/munks87/JustinsGTApage.com
VORTECH S-TRIM completed 7/9/01: 10 & 15 LB. Pulleys, HKS race bypass, serpentine swap. No ET: 8/26/01, Blew motor before track. Rebuild in progess. Beat a freinds 12.9 @ 108 Camaro by A LOT. EST. mid-low 12's as it was. Looking for 11's w/ new motor.

 

I'm not sureif the las post i did went through, but anyway thanks for the info. Which pistons are you guys running? Are they blower pistons? What cc heads do you have. '91 Formula, can you pass emissions? I live near you, and I tried to email you but your adress is no good. Drop me a e-mail, I'd like to ask you a few more questions. I was under the impression that I was better off w/ lower compression and more boost. 8:1 and 15lbs assuming that it was 11:1 total comp, would make more power than 9.5:1 w/ 10lbs totaling 11:1 compression. Right? also the 355 will make more power than larger displacement motors right? thanks for the help.

------------------
SUPERCHARGED 87 GTA: Blk/Gld w/Superam, 355cid Trickflows, forged pistons 9.5:1. Auto 2,600 stall, 3.45 9 bolt disc, Best ET (Nat. Asp.): 13.567 @ 101.900 w/ a poor 60ft. Best mph: 104.3 -*100% NYS emissions legal*
http:// www.community.webtv.net/munks87/JustinsGTApage.com
VORTECH S-TRIM completed 7/9/01: 10 & 15 LB. Pulleys, HKS race bypass, serpentine swap. No ET: 8/26/01, Blew motor before track. Rebuild in progess. Beat a freinds 12.9 @ 108 Camaro by A LOT. EST. mid-low 12's as it was. Looking for 11's w/ new motor.

 

There really is no replacement for displacement. It has more to do with your rod to stroke ratio.

The flame doesnt propgate as well over a larger bore given but I think at the power levels we are at it isnt that big of a concern.

Im using JE blower slugs. They have a dish in them and lowered ringlands as well. 64cc head chamber.

 

Well, 2 things. I'm still mixed on whether or not I'll go 8.5:1 or 9.5:1. And do those pistons come in a 8.5:1 version or close too that? thanks

------------------
SUPERCHARGED 87 GTA: Blk/Gld w/Superam, 355cid Trickflows, forged pistons 9.5:1. Auto 2,600 stall, 3.45 9 bolt disc, Best ET (Nat. Asp.): 13.567 @ 101.900 w/ a poor 60ft. Best mph: 104.3 -*100% NYS emissions legal*
http:// www.community.webtv.net/munks87/JustinsGTApage.com
VORTECH S-TRIM completed 7/9/01: 10 & 15 LB. Pulleys, HKS race bypass, serpentine swap. No ET: 8/26/01, Blew motor before track. Rebuild in progess. Beat a freinds 12.9 @ 108 Camaro by A LOT. EST. mid-low 12's as it was. Looking for 11's w/ new motor.

 

1)Pistons are forged Wiesco flat tops w/ 5cc valve reliefs.
2)Heads are 72cc
3)Passes NYS Emmisions dyno test. Still have original dual cats on car and all smog equipment working.
4)I fixed my E-mail. Ask away.
5)A lower static compression will make more power when high boost is used. High boost being 15lbs and up (good luck with the 6rib setup, I moved up to an 8rib). I wanted some pull before the boost kicked in at 3000rpm. My 9.8:1 CR should be the highest you should go, especially if you have iron heads like I have. I really have no detonation problems.

------------------
'91 Formula
383CI Superram, Sportman II's
SLP Cam 214/224 .470/.490
Vortech V1 S-Trim
5-speed
3.42
12.34@117.04, 1.91 60Ft.
on Drag Radials

 

thanks again for the info. Remeber, I am going to run 15lb at the track and maybe even 15 on the street, on pump gas. So I would imagine, I should go no more than 8.8:1 or 9:1. If i remember,, you said you were running 12 lbs. I havehad detonation problems before, so I want to remain cautious. Do you think 8.8:1 will cut it???

------------------
SUPERCHARGED 87 GTA: Blk/Gld w/Superam, 355cid Trickflows, forged pistons 9.5:1. Auto 2,600 stall, 3.45 9 bolt disc, Best ET (Nat. Asp.): 13.567 @ 101.900 w/ a poor 60ft. Best mph: 104.3 -*100% NYS emissions legal*
http:// www.community.webtv.net/munks87/JustinsGTApage.com
VORTECH S-TRIM completed 7/9/01: 10 & 15 LB. Pulleys, HKS race bypass, serpentine swap. No ET: 8/26/01, Blew motor before track. Rebuild in progess. Beat a freinds 12.9 @ 108 Camaro by A LOT. EST. mid-low 12's as it was. Looking for 11's w/ new motor.