john563

iTrader: (17)

I'm thinking of adding some cubes to my bottom end,and was wondering how bad would these stage 2.5 5.3 heads choke a 408? Should I just go wiht a 383 instead?
Right now I'm a H/C/I 346 in an A4 and put down 435rwhp 407rwt..I'm thinking of forging the bottom end this winter,and thought why not just throw in a 408,but think the heads may choke it real bad..My second thought was to just get a 383 with a ms3/4..
Right now my cam is 232/238 6xx 6xx 111+2 and I like this set upon my 346, but I know I'll need a bigger cam with a 383 or 408.
So what do you guys think throw in a 408 with new cam with my heads or a 383 with new cam and my heads..
What power you think it will put down with the 383 or 408
thanks
john

00 Freak

iTrader: (34)

get that 408 and sell your heads. you might be very close on buying some l92s.

Sales4@Texas-Speed

iTrader: (4)

I agree with 00 Freak on this one. The 5.3's would work alright especially for street driving because of the smaller runner, but to see the most power out of the motor moving to something like the L92 heads would be a good call.

john563

iTrader: (17)

How would these heads do in a 383? I was thinking of going that route,but put in a larger cam such as ms3/4 or I thought about the texas giant,but do you think it will be too big?

Tainted

iTrader: (9)

define to "big"

Does it have to idle perfect, go through stop and go traffic without cutting off etc. etc.?

john563

iTrader: (17)

I dont care about perfect idle,just as long as it does not stall I'm fine

3rdgentug

iTrader: (23)

im puttin those heads on my ls3 block ( 416 )
for what im doing its fine, its not a track only high end only car though. i drive mine on the street and the track

the prc's arent bad heads there are worse out there , they arent going to choke your motor, but yea there are alot of better heads out there if your looking for a track only vehical or are trying to get every single peak # you can get out of your setup.

depend on what you intentions for the motor are is all im saying

Fifedogg

iTrader: (15)

I'm using PRC Stage 1 LS6's w/ the MS3 Cam on my 402. I hope to see 475-500 RWHP out of her, but we will have to see what happens.

john563

iTrader: (17)

Are set ups right now Are about Identical..Same heads and my cam is a 232/238 6xx 6xx 111+2lsa and ported fast 90/90 with a TCIssf 3500stall..Let me know what you put down with the 416...What cam you gonna use in the 416?

I dont think that the heads are bad at all,actually think I made good power in an A4,just dont know if they would be big enough and how much horse power is being left on the table

Sales4@Texas-Speed

iTrader: (4)

I would definately go the 408 route, IMO 408/402 motors make much better power then a 383. If it were my personal car I would buy the 408 SB first and get some nice heads later on down the road, the power will be much better then a 383 with some nice heads.

3rdgentug

iTrader: (23)

ill let ya know if ya want, i have very good froends here in memphis at comp cams in the research and developement dept. they spec me out cams.
like mine in sig. it was taylored for the parts i was using on a slightly conservative note b/c at the time i was planning on it being my everyday car

3rdgentug

iTrader: (23)

also, theres more in the setup i have now, even my tuner said so.
he wouldnt be suprised to get 5 more rwhp and 10 tq is what he told me.
we both know my stalls killing the dyno numbers
the tune needs tweeking down low and up high he left it a little fat on purpose til we can dyno tune it again.

john563

iTrader: (17)

Thats the answer I needed to hear,thanks

john563

iTrader: (17)

anyone else use these heads in 400+ ci ? if so what did it put down

Sales2@Texas-speed

iTrader: (5)

There have been a few result threads since you posted last.

https://ls1tech.com/forums/dynamomet...m6-f-body.html

https://ls1tech.com/forums/dynamomet...ls6-heads.html

Those are the first couple I found for ya. When I find the others, I'll try to rememebr and post them too!

john563

iTrader: (17)

if I use these heads on a 408 with your texas giant cam in an A4 do you think it would break 500rwhp? What do you think it will put down roughly?
just noticed your 427 ls3 short blocks were not much more......you thoughts?

Sales4@Texas-Speed

iTrader: (4)

I think that would be a good goal to shoot for. With the added drivetrain loss of an automatic it will be kinda tough to get all the way up there on the dyno, but remember that the dyno is just a tuning device the track will really let you know how the car is running.

The LS3 427's are great if you are just running all motor, but they do not accept any kind of power adder due to the 4.100" stroke we had to use. When run with the L92 heads the motors will do real well because they can make use of that large valve. It basically comes down to if you are wanting to run a power adder or not.

john563

iTrader: (17)

honestly 500rwhp is alot in an A4 so if I do that I would be happy and no need fora power adder...As far as dyno numbers go I put 435rwhp 407 rwt,but added 373 gears and now put dow 425,so I lost "dyno numbers" but it does not bother me..

Jason 98 TA

iTrader: (4)

I've seen 500rwhp from a healthy 408 with the PRC Stage 2.5 5.3l heads. That being said something like the PRC 215 head could be purchased & them send them in for upgrading to 237cc down the road when you go crazy with bigger cubes!!

The PRC 215 head has already proven itself with the h/c stock bottom end record & indepenedent near 500rwhp results on a stock bottom end m6 car!

http://www.texas-speed.com/shop/item...d=993&catid=40

We're also working on a aggressive 230cc configuration that will feature 2.06" valves & flow over 330cfm on a 3.910 bore plate! This cylinder head would move over to a bigger cube engine without any problem!

SOMbitch

iTrader: (8)

I have a friend making 475 on his 5.3 TSP headed 383 on a nitrous tune. MS4 cam, 3.73's. Full weight car running high tens all motor. I can't remember his exact times on spray but IIRC it is high sixes in the 1/8. The track here is too short for 1/4 + spray.