500+ hp l98 heads 355CI and race gas

Yellow73SB

Well-known member
Joined
Mar 24, 2008
Messages
1,201
I can get any grind I want as a cam maker is less than a mile away from our shop

http://www.camtechniques.com/


The motor is a 350 bored 30 over with mahle flat top pistons, 0 decked, forged crank, eagle h beam rods. The l98 were done by a very good porter, the only we reason we were able to get ours done was because he rents from my uncle. So they aren't complete shit. It's topped of with one of those victor JR knock off intakes and a Holley ultra HP 650 DP. I'll have to get a larger main body for it.

I don't want to spin it any higher than 7500 rpm

What cam should I use to accomplish this? It doesn't need to be streetable.

I am thinking I probably want to get the DCR as high as possible and run a lot of duration, a lot of lift isn't going to do me much good with the l98 heads.

Maybe I should contact a cam company and see what they recommend
 
What are you trying to do ? Do you have a spare short block and want to see what it does with a huge cam or is this your own block ??
Do you just want to play and experiment or do you want the engine to last a long time ??

If I had a spare just for fun I'd try one of those insane 250-260 dur @.050" cams with high compression (12:1) pistons... I guess you need good aluminum heads for that, valve lift can be "adjusted" with higher ratio rockers....
 
I dunno man, I sure as hell no engine expert, but it sure a tall order to get 500 hp out of a set of L98 heads....ain't happening.....IMO....

I figger a budget is in mind...so go for a set of Edel heads....used off ebay or better yet, Craigslist.....

:flash::beer:
 
Thinking about upping the HP on the current motor

When I change trannys I'll pull the motor out so it would be the ideal time to do it, I just wanted something that would be pretty relatively cheap for some extra hp vs building a whole new engine.

Maybe since you say it's not possible I'll have to try even harder now :D

I'd say I have over 400 right now, The car pulls harder than a C5
 
What cam are you running right now ? There might not be much room for improvement. Maybe a lil more top end power but usually it's a trade off and you loose low end power... depends on what you're doing... I imagine that a truck cam isn't all that bad for autoX with lots of cornering and not too many long straights....
 
I won't be doing auto-x only now

I'm going to go to some high speed track events, hence the roll cage :D

Right now I have .550 lift and 236*

I think the duration varies a little bit from intake to exhaust but I lost the cam card
 
Last edited:
that's a lot of lift for a flat tappet (I guess)... 236 duration is as much as I have with my 383.... I think that's as hot as I'd go with a 355 and auto trans..... on the other hand you say it doesn't need to be streetable.... :wink:

I wonder how much improvement (if any) you would see with a for example 242-248 dur cam ... I'd think the heads are the limiting factor already... let's see what other members think.....
 
It's a hydraulic roller :suicide:

We take it to 6800rpm at the moment
 
It's a hydraulic roller :suicide:

We take it to 6800rpm at the moment

I fail to see L98 aluminum heads passing that much air/fuel at 6800 rpm's....to make any power ......

I think someone like TT needs weigh in....I have L98 heads with a LT1 induction on top, all modded up and tigged/rigged with the same computer and it runs like a raped ape, but not sure about anything above 400 hp...i'ts only a 355 afterall....it runs nice, but sure as hell not any 500 hp.....

:clobbered:
 
hydr. roller ..... Comp by any chance ?? might be one step above mine: 236-242 with 550 lift.... about the hottest hydr roller cam, next step up is a solid roller. At 6800rpm I wouldn't run a hrd roller anyways.... the heads you have are no match for the cam.... you might even see (or feel) an improvement with less cam.. what's your CR ? Mahle flat tops have what ?? 5cc dish ?? Zero decked block, let's see:
gggggggggg.jpg


10.7:1..... does that sound about right ? that's witha .028 gasket, with a steel shim .015 it'll be maybe 11:1

I'd leave it alone..... actually I'd be happy if that combo with those heads runs on pump gas..... the cam must be bleeding off a lot of CR if it's not pinging....
 
It's running race gas right now with 38* of timing

It pings on pump gas
 
OK, that means my brain is still functioning or I was just lucky guessing :lol:

all right... seriously.... I believe the heads are holding you back and you won't see any benefit from a hotter cam. Good flowing heads should be on your wish list.... the bottom end and cam seem to be fine :noworry:
 
I guess I'll just work with what I have

I just pulled a big block out of a truck too, maybe this will be built up down the road, my dad seems to want to do it a lot
 
I guess I'll just work with what I have

I just pulled a big block out of a truck too, maybe this will be built up down the road, my dad seems to want to do it a lot

you put that BB in there, make sure you vent the gas cap so the tank don't collapse from pumping fuel out too fast.....

:bounce::bounce:
 
I guess I'll just work with what I have

I just pulled a big block out of a truck too, maybe this will be built up down the road, my dad seems to want to do it a lot

you put that BB in there, make sure you vent the gas cap so the tank don't collapse from pumping fuel out too fast.....

:bounce::bounce:

What does 110 racing gas cost per gallon these days?
 
I can get any grind I want as a cam maker is less than a mile away from our shop

http://www.camtechniques.com/


The motor is a 350 bored 30 over with mahle flat top pistons, 0 decked, forged crank, eagle h beam rods. The l98 were done by a very good porter, the only we reason we were able to get ours done was because he rents from my uncle. So they aren't complete shit. It's topped of with one of those victor JR knock off intakes and a Holley ultra HP 650 DP. I'll have to get a larger main body for it.

I don't want to spin it any higher than 7500 rpm

What cam should I use to accomplish this? It doesn't need to be streetable.

I am thinking I probably want to get the DCR as high as possible and run a lot of duration, a lot of lift isn't going to do me much good with the l98 heads.

Maybe I should contact a cam company and see what they recommend


If it does not need to be streetable and you are running 110 octane, what kind of DCR would you be looking for?
 
I guess I'll just work with what I have

I just pulled a big block out of a truck too, maybe this will be built up down the road, my dad seems to want to do it a lot

you put that BB in there, make sure you vent the gas cap so the tank don't collapse from pumping fuel out too fast.....

:bounce::bounce:

What does 110 racing gas cost per gallon these days?

It hasn't gone up much I believe it's at 7 dollars
 
500 horses? I'm not seeing it happen with L98 heads. Port size too small, you can't get large enough valves in there. IF you can do it, I want to know exactly what you did :D
 
Top