5abivt

I havn't looked into it so forgive me for asking. My engine builder reccomended going with 15 or 18 degree heads saying theres an easy 100 hp + on the table over LTx castings. I thought about manifolds and tossed the idea. Maybe I bailed too soon? My reasoning behind not looking into it was that I already spent money on my lt4 manifold to have the dizzy mod done, custom fuel rails, throttle body etc etc that I wanted to reuse.

I was thinking to have gone with a sheetmetal intake to make the heads work on my ltx block but I said no to that idea as well. If i was going ***** out on a manifold with sweet heads I would want an aluminum block or at least a really nice block with a bigger bore to start.

AKS Racing

Custom manifold, but not that big of a deal to mod a carb manifold to EFI. There are so many examples floating around on the net.

Additional HP is available through the revised valve angle (standing the valves up; like the LS series engines).
Aaron

BrianCunningham

This if CF member Insanity's car, it's a 434sb and I recall he's running 18deg heads

AKS Racing

Brian,
You need that engine in your car with the blower. Now that would be FAST!
Aaron

mnstrlt1

"can" you even use a different (non-LTX application) head on an LTX block? I think you'd be looking at custom intake, custom headers, possibly a stand alone to run the combo, etc...

BrianCunningham

Can you yes.

It's a royal PITA though! That's why I went the blower route. A 434 would be nice, and yes you can modify an aftermarket block, not exactly for the weak of heart. Insanity's car is no longer an LTX BTW.

If my S-trim doesn't crank out enough power for me, there's guy's running 10's with it, I'd send it back to Vortech for a T-trim upgrade

88BlackZ-51

Mike. I guess you have to ask yourself, is it worth it? What are your goals for this motor? I would go with something proven.

Steve85

Not that I am aware of and I searched a lot too. Now Hilborn injection for 18 degree you can find.

I did hear from a member a few months ago that converted a miniram. Perhaps the LT4 manifold could be converted.

I never got pics or very good description of how it was done. I will try to get his username...may be worth a shot.

I talked to Hogan before having the single done and they wanted $2600, a little much for me.

BrianCunningham

That's right I forgot about Hilborn, Kinsler sells them.

Nice setup, one throttle for each runner.

If you want to run MAP you need to hook it up to each one via a manifold.
If you want to run MAF you need to enclose it somehow.

5abivt

what would be ideal for me would be to run a custom manifold with a larger plenum, that still has all the same hookups as an ltx manifold so i can reuse the rails and throttle body and brackets etc for the cable. this way theres adequate hood clearance and I would still be able to use the stock sensors (map) and intake that I have for the forced air.

Interesting im going to start doing some digging into this...

Orr89rocz

modded carb manifold with a elbow would be the best bet

Steve85

The problem is the heads are taller and the intakes are taller than there 23* counterparts. My 4 barrel style TB is only 1.5" tall and barely cleared the hood with no filter on it...barely.

If you can get an 18* "base" (lifter valley and plates that bolt to the heads) then have the LT4 manifold adapted to it you could keep all you're hookups. maybe find a single plane being dumped on eBay and literally just cut the runners off leaving a nice little 18* ready "V".

I wish I would have thought of that with the MR before cutting my hood...oh well.

BrianCunningham

Those 18degree heads you builder wants to install, how much do they flow?

The aftermarket 23deg heads have come a long way.

EDIT:

also what rpm are you wanting to turn?

Are you running a bigger displacement? LTX blocks are limited.

Are you running boost at all?

Orr89rocz

just get a new hood its worth it for that good power

the other alternative is just to run all pro 245's which are 23 degree with a big inch motor/big bore and that will be almost comparable to a 18 degree motor

yedister

I have Brodix 15* heads with a Mini Ram. The 18* and 15* ports are actually closer to the block, but the intakes for those heads are taller than the Mini Ram. If you can get your current intake to mat up the 18 / 15* heads then there would be no hood clearance problem. If will cost money in machine work. There is a member that had Wilson Manifold match & ported Mini Ram to his heads. I believe the heads had a raised runners. each port of the Mini Ram flowed 400 cfm. Cost was $2000.00 My heads flowed 340 cfm by themself with the ported Mini Ram (not ported by Wilson) 336 cfm.
My suggestion contact Wilson manifold and see if they can help and how much will this help cost.

yedister

The Allpro require special cut pistons, this is only a problem if you already have pistons

yedister

Just saw this
http://forums.corvetteforum.com/show....php?t=2166503

Orr89rocz

Yeah i've seen that about AP245's, but dont 18 degree heads sometimes require special pistons anyway? If you have 18 degree pistons then yes get 18 degree heads

I would think if your even considering needing 18 degree heads, you'd have the engine build plan set in stone to use 18 degree heads and not a conventional 23 degree piston. Same with the AP245's.

Another best bet would probly be a raised runner head like AFR's 215 head. Pretty bad *** for a 23 degree head, just have the intake runner welded up on the miniram/LT1 intake and raised up... as well as the injector ports if necessary

Couple of guys on thirdgen have done this to TPI manifold bases to get a larger/taller port just for conventional 1205-1206 port heads

EDIT: yes a intake elbow and converted carb manifold was what i was thinking of when i said convert a 15-18 degree intake to EFI. But even then it may be pretty tall, probly as tall as an HSR which dont clear but you could probly mill the intake top down and maybe have a custom low rise but wide plenum built to fit

BrianCunningham

Nice! Any pictures to share?

SloRvette

This was done for a set of raised runner 23 degree heads. The ports would need to be raised just a little farther to work with a set of 18 degree heads.

This intake is for sale.