Jeffsvettes

I have a 81 with L48, 24K orig. miles. The engine is all original and has never been appart.Runs like new with no issues.I would like to increase it to about 400HP while retaining the orig crank and pistons if poss.
It must be a very reliable and streetable combo. It will not be used for strip or autocross. I am willing to install a different hood with a few more inches of clearence if needed.

I will be swapping the auto trans for a T56 or t5 at the same time. Also willing to swap the rear diff. if needed.

Would like to keep budge for engine mods only at around $3000. but willing to go higher if needed for better perf. or reliability. If it can be done for less better yet.

I will be doing all the work so labor costs do not need to be included in the budget. If it makes more sense to do a crate engine swap say so.
Jeff

patraw03

Jeff,
I've been doing a lot of research lately on HP upgrades for my 69, I don't know a lot about the 81, but with a 3000$ budget, you could easily find a kit blower that you could install yourself. You would have to chop the hood up though for that to work.

If it is fuel injected (cant recall if they were yet) Super or turbo would also be in that budget. You may have to switch out the injectors with that, but it would easily put you over the HP you are looking for. Plus you could knock that out in a day.a

I'n my opinion you won't find a crate motor worth a darn for under 3 grand. Going to a junkyard and pulling a LS1 motor with all the wiring might be a better option. I found those for as cheap as 450 dollars (as-is) You take a risk, however if you put it on the stand and it cranks over, you made a hell of a buy.

I'm not sure what the emission laws are in NJ, but running straight pipes or a competition exhaust, will up the HP as well. Mixed with a new intake and carb, will possibly give a 10% gain. Speedway motors, makes a spacer that accommodates a 3x2 carb or a 2x4 carb on the stock manifold for a fraction of the price. I dont know the science behind it, but it may be worth a look.

Good luck with your project.
Mike

Mark Riles

These are good suggestions but if I might add a few points. A blower kit is a good, tried, and true method of bolting on power. But being an L48 his bottom end might not support that kind of a power increase for long. It might but it also might not. If the caps were splayed with 2 extra bolts each and the rotating assembly was switched for forged pieces from an L82 then it's a good way to go without spending a ton of coin. The LS engines are cheap from the salvage yards that's true but there are a lot of costs that add up after purchasing just to get it installed and running properly. You'll double your budget trying to do an LS swap.

patraw03

I'm not too familiar with the L48, I wasn't sure about the blower.
As for the LS swap, it seems he knows what he's doing and has some sort of shop, if he does all the work himself, you think it would still be expensive? If he could get the ECU and wiring cheap with the motor? He was talking about replacing the transmission and rear end anyways.
I'm sure a suspension and brake upgrade would be good to go along with it. What are your thoughts?

63mako

With a stock bottom end wanting 400 hp go with a set of 65 CC AFR 195 eliminators, Felpro 1094 head gaskets, this cam kit.
http://www.summitracing.com/parts/HRS-CL111145-10/
and this intake:
http://www.summitracing.com/parts/EDL-2601/
You can use your stock Quadrajet, Might need a little rework.
Headers into true dual exhaust. This should get you real close to 400 HP, be very reliable and everything is matched to get your power under 6000 RPM to save that cast bottom end. Should be able to do it all for $3000

tyancey00

For 2 grand you can buy a 383 short block from summit. You can buy heads cheap....and everything else you need would be off the old motor. That way you have original motor if you want to go back original in the future...

qwank

A stock '81 has an L81. Its pretty much an L48 with an L82 intake and a computer controlled carb. Its going to be really hard to get 400hp out of the lower end because of the lower compression pistions. Even 300hp would be a feat. I like the 383 shortblock idea. That's the path I will be heading with mine when the time comes.

Jeffsvettes

Thanks to everyone for the responses.

1-I have considered the LS swap but for my mid year.

2-qwank is correct it is an L81. I was thinking of the engine I have
from an 81 I parted out, but I don't know its history (was running
when removed)

3-63mako will your suggestions still work with the L81?

4-Would I be better off with some type of short block swap as
suggested by tyancey00?

5-I also have the L48. Would I be better off having this
block machined and start off fresh. What parts would
you suggest and what would their costs be. I can
increase my budget if this is a better option. Maybe
someone would be interested in the L81 and trans to
offset some of the budget.

Thanks for the help
Jeff

63mako

Yes. It will work fine. The heads will work if , down the road you decide to build a 383. The operating range of the cam peak @ 5600 rpm. A rev limiter is money well spent when you push a cast bottom end to the 400 HP range to limit rpm because it will feel like it wants to keep going and so will your right foot and right brain.