4.1vs 3.8, power gains with using the same heads.

[cool 84]

Since my project is getting closer to completion, I was wondering just how much more power a 4.1 is worth with the same stuff bolted up top. I had to get rid of my GN1s due to lack of funds so I have ported irons, the same as with my 3.8.

I figure I'm going to have faster turbo spool, more low end torque, more midrange, but I've been wondering, is the 4.1 worth much power in the upper rpm range considering the limited airflow of the heads and intake?

[Intercooler]

Cubic inches make it better the whole way. Considering about 2 HP per cube should be 50 HP or so.

[azgn]

problem is, 4.1's are very weak...hardblock needed

[Intercooler]

Originally posted by azgn
problem is, 4.1's are very weak...hardblock needed

I guess I will find out with the one I have sitting on the stand one of these days. Only thing I can see is the decks and lifter valley. Only the deck concerns me....rock on!

[Quick6'n'-K.C.]

Originally posted by azgn
problem is, 4.1's are very weak...hardblock needed

do you know anyone or have pics of how the hardblock is done?

thanks for any info

BW

[cool 84]

I didn't want to turn this into a 4.1 strength debate but I'm a little worried too. I want to know if anyone has ever actually blown a hole in a cylinder or if it's just hearsay like a lot of things on the internet. I've always heard the hotair block is weaker than the IC block but I had a pretty potent combo and not a bit of problem. Duttweiler himself told me the hotair block is no weaker it just doesn't look as pretty in the valley area and it's possible for cracks to develop from the rough casting.

I talked to my engine builder (who is an engineer and had a part in the Buick Indy program) and he flat out wouldn't do hardblock on my street driven car even a small amount. He said it would hold up as long as it's in a good state of tune. Mine's .035 over so we'll see.

[Quick6'n'-K.C.]

i didnt come anywhere close to breaking a block-

but i did purchase a car in the past that it turned out to have a 4.1 litre engine in it, .040 over,stock cam, stock nylon timing chain gears , mild ported heads and intake-

went 11.80s no problem on nittos at 118+ with a looooooose 9 inch non lockup convertor

so my answer to your first post is, yes its like having more power all the time, but i felt it was limited on the upper range-
i think i was just afraid to rev it up past 5200ish??

its the only turbo regal that i was able to blow the tires away thru 3rd gear on real radials with 3 guys and a full tank of fuel-

it had a te45a with .85 housing spooled SUPER FAST-
MSD 50'S, ATR 301 DOWN PIPE, dual 3 inch exhaust

[Whitettype86]

I have block hard 1.75" from deck in my 4.1 and plan on driving it sometimes here and there. Also the lifter valley has been Ti-putty to strengthen that area. I have a 4.1 reciepe from the man Lonnie diers. He has giving me great knowledge on the 4.1 and a also have Nick Micale helping out with the dirty work on this motor. I plan to see what a 4.1 can do and I know they have potential if built right.

[cool 84]

Originally posted by Quick6'n'-K.C.
i didnt come anywhere close to breaking a block-

but i did purchase a car in the past that it turned out to have a 4.1 litre engine in it, .040 over,stock cam, stock nylon timing chain gears , mild ported heads and intake-

went 11.80s no problem on nittos at 118+ with a looooooose 9 inch non lockup convertor

so my answer to your first post is, yes its like having more power all the time, but i felt it was limited on the upper range-
i think i was just afraid to rev it up past 5200ish??

its the only turbo regal that i was able to blow the tires away thru 3rd gear on real radials with 3 guys and a full tank of fuel-

it had a te45a with .85 housing spooled SUPER FAST-
MSD 50'S, ATR 301 DOWN PIPE, dual 3 inch exhaust

That's what I like to hear!