Stage II heads v.s M&A Ported

[Turbo231]

Right from the start I know the two are totaly different ie. Cam,headers...
I just check the fourm every day and Kendall
got me thinking about it the other night on IRC. I'm in the begining stage of building a 3.8 Stage II block. I have Stage II ported heads and M&A ported heads a BGC intake and ATR headers. What would be the best combo to run on my street/strip GN? By street/strip I mean I drive it now only to where a big mouth is to shut him up with a Little V6.
And to race at the track, about 2k Miles a year. I really liked the Idea of full stage II and just pull my current motor that is still strong to keep. So it all boils down to Prodution based or Stage II based heads and what stroke for a 3.8 Stage II block.
So I hope this gets some action in the forum.

P.S
I was planing on a soild roller with a minumum of 220*

[GNTURBOET1050]

This might help sway ya if you want to run stage heads, you will need to buy headers $
also they don't fit with the heater / AC box
so you have some money and time to make it fit in the car with the heater and AC. So it would be less of a pain in the azz to stay with prodution based top end I know because
I have fitted my all staged motor with ac
and i am still not done but close.

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Michael Gardner
84GN 12.93@103 STREET
86GN 10.57@128RACE/STREET
95 RIV STREET

[inno51]

I have a Stage II 4.1 274 being built that I did seriously consider putting in my street GN. The one issue is in order to fully utilize the stage II head you have to compliment it with enough turbo and RPM. You will sacrifice a little bottom end and being it is a 3.8 you are building I have been told that is not the best choice because of the smaller bore size (valves shrouded). Since you will be driving it on the street a Champion or M/A head will be your best choice.

I got a Champion "R" series fully ported 274 going together for my street motor. As long as the heads don't crack, it will be more than fast enough for the street.

[990 T]

I thought about this as well, and for my 274 stage 2, I am going to run basically unported stage 2 aluminum heads, but with some chamber work. Valve size will be 2.02/1.60. I want to keep the velocity up, and keeping the ports smaller will help. My goal is high 9's, so my criteria may be different than yours. I also plan on running 9:1 compression, as it will be mostly a street car. Flow numbers that I have heard kicked around are something like 280cfm or so for al. stage 2's stock, ported anywhere from 340 to 400; Ski's ported M&A's done by Ruggles flowed something like 300 cfm; and stock M&A's I don't know. HTH, and good luck.

[Mac in SD]

Originally posted by GNTURBOET1050:
So it would be less of a pain in the azz to stay with prodution based top end I know because I have fitted my all staged motor with ac and i am still not done but close.

Michael, my 274 S2 headed motor is close to going in the car. I've got the ATR headers and heater box mod kit, and was planning to run A/C... What complications have you run into running A/C with S2 heads? I know I've got to do some work with the stock accessory brackets, especially the support bracket from the #1 exhaust header bolt to the back of the alternator, as well as the lower support bracket to the A/C compressor. Any tips? TIA.

[Turbo231]

I'll give a little more info on what I'd like to run:
9-9.5:1
240* Solid Roller
7-8K Shift?
4-5K stall
C-16 Always
So now what?

[HighPSI]

I would go with the M&A's and put as much stroke in it as you can.

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[Kendall Frederick]

Originally posted by Turbo231:
I'll give a little more info on what I'd like to run:
9-9.5:1
240* Solid Roller
7-8K Shift?
4-5K stall
C-16 Always
So now what?

The M&A head with the smaller motors has been done more, and should run well...Neal Steward's 252 is/was a stroked 3.8 with less cam than you're contemplating, and he's run bottom 10s.

Some rambling regarding the Stage II heads: I think compression, turbo sizing, and cam will affect the RPM range more than head port size. I like the 9.5:1 compression; I'm doing that with my 277". I think I would run a little less cam duration in the small motor to try and bring bottom end torque up, personally (maybe 220 range?). The 240+ duration cam will be *very* choppy in a smaller motor unless it's got a very wide lobe separation.

I think once it spools, you'll have all the torque you can use and then some. I'm going to keep plugging on mine, and I'll try to report honestly, positive or negative.

Good luck!



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Orange Park, FL
various cars, some running

[Turbo231]

Cool!! This is what I'm talking about!!
A board that offers real world info!!
(Not,my chrome tip gained me 0.2 in the 1/4)
I'll be calling Comp Cam's soon, I'll see what they say.
But from 220-240 was my range but sounds like more to the lower side 225-230 ?
I'll report back what Comp recomends.
Keep up with the feed back!!
I love it!

[GNTURBOET1050]

Mac as far as stuff i have run into first
install your headers on your motor and get them to fit i had to send mine back to ATR
because the crossover did not line up. next
you need to do the heater core box chop and
just srew in place the new box side do not
glass it into place, till you fit the new heater core and fit the motor with the headers and the valve cover if that all works
out then try the down pipe out on the turbo
get everything worked out and clearing the box before you finish the box so the motor need to go in and out with a trans some fun
P.S i also put a mid plate in so mines been in and out about five times.

[This message has been edited by GNTURBOET1050 (edited July 13, 2001).]

[HighPSI]

Brad,
I would suggest a Comp 224/224 cam. I ran that in my 274 motor down to 9.4's. With my 9.5:1 compression the car pulled over 20" of vacuum @950 rpm.

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[Spot U 1]

GNTURBOET1050

Are you saying you are running a mid-plate with ATR's single turbo set up?

If so, then could you give details as to the install of this unit. I have heard of several people that say you can't do this because of the crossover pipe. I want to put a mid-plate in my car, and I've been looking at going twin turbo partly for this reason. I'm very interested in the specs for this.

Thanks,
Ken Hagood

[GNTURBOET1050]

Ken it can be done it's a lot of work fitting
the thing but i did make it happen one thing i found in doing the mid plate was the engine
and trans was not in the car in a straght
line which did take some time to correct so if your going to do this don't be in a hurry.
you first need to check this and get the engine,trans,rear in a straght line.Why?
because the mid plate is forever once it is welded in as fare as i am conserened i did make mine a bolt in it is 1/4" aluminum and
it can be chopped down to fit with the ATR
headers you will have to bang the trans tunnel seam flat which helps with getting to
the trans bolts and fitting a sheild on the trans.the drive line needs to be in a straght
line but it can be off a inch from trans to
rear lot's of measuring under the car can you say plum bob,straght edge,and square.

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Michael Gardner
84GN 12.93@103 STREET
86GN 10.57@128RACE/STREET
95 RIV STREET

[Spot U 1]

Michael,
Did you custom make your plate or did you start with a mid-plate kit?
Thanks for the info.

Ken Hagood

[This message has been edited by Spot U 1 (edited July 15, 2001).]

[GNTURBOET1050]

Ken I started with a mid plate kit which was
a 1/4" aluminum and cut it down to fit, between the frame rails. but first i made a
template out of cardboard and cut it down to
fit then traced it onto the plate then cut it.are you with me?

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Michael Gardner
84GN 12.93@103 STREET
86GN 10.57@128RACE/STREET
95 RIV STREET