Fia69

What is he most power to be had using thies heads, LT-1 duel plane , 500 lift max cam flat tapped. Would like a broad to high rpm range
bore and stroke are opean to any combo.

REELAV8R

Rule of thumb is to double the max flow of the intake valve to get the max potential of the head.

So if they flow 275 @ .500 lift that would be 550 HP.

Fia69

Thank you. Does that mean given the other restrictions a 13 to 1 motor
With a 5degree roll over on the head?

REELAV8R

Not sure what you mean. All I'm saying is given a very good build you can achieve those numbers.

gkull

This figure would only be true for solid roller cammed motors with everything optimized to operate at or near 100% VME big carb, single plane intake, high compression, and tuned headers without back pressure.

Years ago I came across an article with the relationship to VME (Volume metric efficiency), head flow CFM, and Cam type. Some group of people came up with all these charts and graphs and it became the basis for programs like "Desktop dyno"

I don't remember the exact numbers, but your H flat cam build in a 383 motor with 275 cfm of flow was more like a 1.5 times factor for 412.5 hp. You can buy a 430 hp 383 crate motor, but it is more optimized.

then they went onto the solid lifter motors with a 1.62 factor. Then H-rollers with a 1.80, and finally your solid roller with 100% VME approaching 1.90 factor. Again they were talking about a streetable 383 SBC.

So never quote some 2 X CFM value! The posters .500 lift h-flat cam would probably be lucky to achieve one HP per ci. You have to do a reality check. The original Z06 vettes made 405 hp with a 7000 rpm roller cam

REELAV8R

He asked for the MAX potential of the head. I gave him the rule of thumb for an optimized set up.
He didn't ask for estimated HP for his set up.

Fia69

Sorry for the confusion, I did not state my question correct. So let's back up. The heads in question are stock but with a great valve job. The cam is a variation of the Dutove 30/30 ,486 lift less .016 lash 104 centerline and
Around 250 duration at .050. Intake is stock as stated compression stock
is 11 to 1. I do not believe this combo can put down over 400 at the rear tires . A bit light for my purpose. I as about the heads only as I was trying
To find the weakest part in the combo. Actually I thought the heads were the better part but never seen them used on anything 550 even at the crank. All in all I am trying to make about 520 at the crank with thies parts
,no easy task. That is why I mentioned rollover the heads ,up the compression and use some great rings . Even then I just do not know. Please understand the parts to be used are not of my want but built to speck.

Fia69

Sorry for the confusion, I did not state my question correct. So let's back up. The heads in question are stock but with a great valve job. The cam is a variation of the Dutove 30/30 ,486 lift less .016 lash 104 centerline and
Around 250 duration at .050. Intake is stock as stated compression stock
is 11 to 1. I do not believe this combo can put down over 400 at the rear tires . A bit light for my purpose. I as about the heads only as I was trying
To find the weakest part in the combo. Actually I thought the heads were the better part but never seen them used on anything 550 even at the crank. All in all I am trying to make about 520 at the crank with thies parts
,no easy task. That is why I mentioned rollover the heads ,up the compression and use some great rings . Even then I just do not know. Please understand the parts to be used are not of my want but built to speck.

Fia69

I am trying to get my head around the current record for 2B in the nccc Corvette association .
It is a corrected 11:30s in a 3200 lb.car using a 350turbo. To me that figures about 420 at the rear tires ran 119 mph. That is the reality of the class , I an just trying to figure what's up. Yes say he has a state of the art trans and is on drag radials. That is real fast for a supposed stock 1970 LT-1 with a .486 lift cam regardless of the ramp speed do you not think
Keep in mind he supposedly is using stock camel hump's probably 186's.

gkull

You can't do it with old technology 30/30 cams. I used totally trick ported 186 casting with 2.02 Manley proflow valves, screw in studs crane roller tips, crane solid flat 238/248 114 1.46 dual springs titanium retainers 355 ci. Shifting at 7200 rpm with a pro built th350 4.11 gears and 10x28 Goodyear slicks. 500 pus rear steal spring 1 3/4 hooker SC headers 14 collector extension

later on I installed 292 casting heads with 2.055/1.625 Manley proflow. I got my weight down to 3000 with nhra 6 point cage

those old cams just don't make hp because of the slow ramps and lower lift you need to get up to nearly. 600 lift to make power

Fia69

I agree yet according to nccc records it is done and been standing record sense 2010 I think.

gkull

I would look at the rule book really close. Most historic racing says solid lifter cam and a max size on the lifter bore. They don't allow roller tips, but you can buy the comp cams super strong non roller tipped steel rockers. I would find the 292 heads they were an over the counter GM iron turbo head. they are @ 200 cc intake with a superior chamber design. the valves are spaced wider to accommodate 2.055 intakes and they are taped for screw in studs.

186 casting like mine I had $1000 in porting and machining for screw in studs and large dia. hardend seats. The valves only had a small outer contact point which really increased the CFM.

I also used an extrusion honed LT1 aluminum intake manifold port mated to my ported heads.

I used my 79 L-82 block and forged bottom end. nice crank and rods. windage tray. I had wiseco forged light weight pistons and floating pins. I had my rods bronze bushed for the full floating pins and the whole assembly balanced. I used a 6.125 dia. light weight fluid damper and smaller aluminum crank pulley to under drive the alternator and power steering pump.

Did anybody verify the CI and parts of this so called stock 2010 record setting motor. I was a historic racing mechanic for 10 years and I worked on some very creative cheater motors that came through our shop. I think the best one was a destroked 400 block around 385 ci bored out .060 over with a sleeved block. It has Dart 18 degree aluminum heads that looked exactly like double hump heads with raised emblems. The heads had been painted with magnetic paint so tech inspectors would think that it was iron headed

GOSFAST

We don't care for or use Dart heads generally speaking but we do get to dyno many (customer supplied) and can say this, on a recent build with the Dart SHP 200 runner we made 500 HP @ 5800 and 480# Torque @ 4800.

This was on the 383" retro-hyd roller platfrom with a 9.75:1 C.R. Comp (12-443-8) 242*/248* x .576"/.562" x 110 LS. The roller setup alone helps to add about 30 HP on top!

On a side note, we are now using thrust plate/stepped nose cams on these early builds!

Thanks, Gary in N.Y.

P.S. If you step up to a decent mech-roller (street-style) these heads get you to 550+.

Fia69

Does anyone know the et and mph for a 70 corvette with an LT-1 motor in NHRA stock eleminatior? I understand that NHRA rules are more opean than nccc rules for 2B. Thanks.
I mention the dart 200 platinum as I would think they would flow as much stock as the 186
Castings cleaned up.

Fia69

The nccc rules require production heads only as well as stamped rockers and production lifter
bores.

Fia69

Also stock crank and rods. Rods can be floated, pistons can be a stock replacement, so a stock eleminatior pistion should work. Gasket match 1/4 in. On heads. Any valve spring and retainer , I figure bee hive type using stamped rockers. I have seen the dart 200 platinum done as a double hump, very convincing.

Fia69

Let's take this thread another way and think F.A.S.T. They run factory appearing motors on wide ovels . We have now any cu in. Any cam and compression still a 780 carb. What h.p. Could be made using the factory intake and carb, . This combo would have to run thru a closed exhaust system . L-88 vetts and hemi's are the fastest but I would think a LT-1 vette would do well plus now we have some power.

ajrothm

Are you trying to build a "stocker" or class racer?

Fia69

I was giving thought to the nccc class 2B . And was trying to figure just how it is that fast. So far the suggestions for making 420 at the rear tires out of a LT-1 using Nccc class rules for 2B has most lost including me. So thought I would take a look at F.A.S.T. . It's stock appearing . I am trying to see by their records how fast they are when just looking stock. Yes I am trying to build a class racer, just trying to see where I may be compeative.

Jebbysan

I have the Dart 200 Platinums and I am pushing a solid 500 horsepower.
It is a 406 with a Comp 292 Magnum cam and a Team G.....worked 750HP carb up top......
Over 400 ft/lbs. torque available from 2500 to 6000........

I believe the Dart 200 will support 550 horsepower or better.....the SHP head? No.

Jebby