faulball67

iTrader: (2)

Just what it says. I've got aluminum L98 heads from a 87 corvette and I'm trying to find out if anyone has the FULL head flow specs. If possible at different inches of lift so I can plug it into my dyno sim.

Camaroz29

iTrader: (3)

Prepare to cry........

http://purplesagetradingpost.com/sum...%20L98%20Vette

F-BIRD'88

These heads work very well when fully ported.
The stock as cast flow numbers are modest thou.

Turn the computer off and get busy porting these heads.

Camaroz29

iTrader: (3)

Thought about porting mine as well, but the prices looked steep so I just picked up a set of 190cc heads for 800$.

F-BIRD'88

????

Camaroz29

iTrader: (3)

A full port job isn't cheap, even most of the mainstream places like AI, portpros, LE, etc. charge well in excess of 1000 bucks. In another post on heads we discussed the 1700$ pricetag that LPE charges.

mw66nova

iTrader: (13)

apparently, he wasn't considering that he could do it at home with $80 worth of equipment and a few hours of his time...

Camaroz29

iTrader: (3)

Trust me, I'm poor and would love to save $$, but anyone can port, not everyone can port well. I'm sure it isn't something I can just pick up a book on and get professional results. You should have seen my projects in shop class back when I was in school.

F-BIRD'88

If I can do it , so can you. You do not need to be a professional to get good results. Reading a few $10 books and practicing on a old scrap head helps. Skill comes with practice. Patience is the biggest skill you'll need to develop.
Any one can drop a cylinder head off at a speed shop and say "port 'em" and pay the big bill they hand you.
The average engine builder's (or his apprentice) total head porting knowledge probabily came from the same books
you can read for $10. Some, a lot less.
Usually, because the job is so time consuming, the job gets handed to the apprentice.

You'll get within 10-15 cfm of the best head porter on a max effort job on these heads..
You'll be much further ahead from where you started.

They flow just under 200cfm stock. you can easily get 230 to 240cfm yourself at home. Thats enough to gain 60-80hp over stock. All it will cost you is your time.

faulball67

iTrader: (2)

My problem is that the heads were already on the engine when I bought the car. I had to check the casting numbers just to be sure. It was already set up for racing and had quite a few parts already. I'm not sure if the guy had already had them ported. Guess I should have thought of that when I had the entire engine out. I know I have the skill and patience to port the heads, and the kits from summit are super cheap. I just don't want to have to pull the heads back off. It's such a P.I.T.A. It took me forever to get my new rockers set right. Anyone got the flow numbers on their heads from after porting?

F-BIRD'88

Lingenfelter L98's flowbench results

fyi, got these flowbench numbers for the LPE cnc-ported L98 vette heads if anybody's interested:

in. ex.
--------------------------------------
.200 140 116
.300 198 157
.400 242 185
.450 249 195
.500 254 199
.550 260 203
.600 263 206


intake runners = 182cc
chambers = 63cc
valves = 2.00"/1.56"
valvesprings: seat pressure 130# @ 1.900, open 400# @ 1.34

faulball67

iTrader: (2)

I just ran all the specs you gave me for the lingenfelter heads against the specs for 23 degree trick flows on my dyno sim. The trick flows slightly out performed by maybe 5-10hp up until 5000rpm. Then the Lingenfelters pulled away. At 5000-6500rpm the lingenfelters pulled 5-25hp more.

Looked as follows

Lingenfelter heads
rpm HP Torque
2500 154 308
3000 195 341
3500 247 371
4000 303 397
4500 357 416
5000 404 424
5500 439 419
6000 458 401
6500 470 380

Trick Flow 23 degree heads
rpm HP Torque
2500 161 316
3000 205 337
3500 257 385
4000 308 405
4500 358 418
5000 400 420
5500 429 410
6000 441 386
6500 446 360

I got these results using a standard 350 with a 750 carb, single plane intake, large tube headers with mufflers, and the cam file for a comp cams magnum 282/282 cam shaft.

Sitting Bull

And you WILL pay Lingenfelder over $1000 for that CNC port and polish job on simple L98 heads.

Or you can follow the link at the end of my sig and save major dineros. Alas, it is up to you

Sitting Bull

PS

Vader has even posted some nice templates that will work fine for L98 aluminum heads. Use your search button.

faulball67

iTrader: (2)

Not in a million years. I'll port and polish myself before I pay $1700 for those. For that kind of price I'd rather buy a set of full race heads. I'll becheap for now and buy a kit for $30-$40 and be happy. Stock flow with a 150 shot of nitrous is plenty for now. I've got to get a cage put in before I get to far.

kdrolt

Corvette L98 heads are not all the same.... due to the progressive changes/upgrades made to them since the mid 80s when they were introduced.

The first version wasn't really any better than the iron L98 heads. The use of D-port exh changed that; there have been minor improvements since then.

See a summary here.

What they flow depends on how old they are and how many factory upgrades they may have had. IIRC even the oldest versions of the aluminum 113 casting can be ported to the spec level of the ones you can still buy from GMPP, you just have to DIY. HTH.