18 degree Head 434 SBC Combinations

[Jason G]

How much power are some of you making with 434 or bigger cubic inch SBC's using 18 degree (or other) heads?

What head, minimum CSA, runner volume, valve size, flow, intake manifold, and cam are you guys using. Peak HP and TQ RPM?

Any information you would be willing to share would be appreciated.

Thanks,

Jason G.

[cboggs]

1,000 hp possable with a well built ( no nascar take off junk ) SB2.2 head, .. that's what I'd do.

to figure the port cross sections etc we need information about the combo.

bore / stroke, cam lift, rpm for peak power, car weight, converter, etc.

Curtis

[RRBD]

Pump gas?

[cboggs]

Pump gas?

is for granny's station wagon, ..

Curtis

[10.90streetcar]

Not meaning to hi jack the thread. But what kindda power would a 434 make with Junk Take Off NASCAR Heads?

[cboggs]

Not meaning to hi jack the thread. But what kindda power would a 434 make with Junk Take Off NASCAR Heads?

850 is possable, ..

Curtis

[roller]

what's the csa on out of box 18x? would they work on a 420, 12.5 comp. 7300 rpm?

[OldSStroker]

How much power are some of you making with 434 or bigger cubic inch SBC's using 18 degree (or other) heads?

What head, minimum CSA, runner volume, valve size, flow, intake manifold, and cam are you guys using. Peak HP and TQ RPM?

Any information you would be willing to share would be appreciated.

Thanks,

Jason G.

2006 EMC engine design? 434 is the size this year.

[SStrokerAce]

what's the csa on out of box 18x? would they work on a 420, 12.5 comp. 7300 rpm?

MCA is 2.15 on them.

You should have them ported to suit the setup.

Bret

[Jason G]

Curtis,

SB2.2 is what I likely should have done. Too late now. I'm not making any more changes at this point. The season is nearing and I just don't have time to back up at this point. The engine is built and has been on the dyno and the results were WAY, WAY less than expected.

Granted there were a few issues on the dyno and it was not completely dialed in, but even still it misses the mark.

This is not for the EMC.

The engine will be run on VP - C12 race gas.

445 SBC
9.325" deck height Dart Iron Eagle block
4.145" bore JE 2.5cc dome pistons - 13.87:1 true compression
4.125" stroke Callies crank
6.125" Lunati billet rods
Canton pan with tray and scraper
9-10" of vacuum
Crower 1.6 ratio SS shaft rockers
Jesel Belt
Isky Redzone .185" offset roller lifters
Isky 282/286 @ .050, 108 LSA/180 ICL, .709"/.709" gross lift. .200 duration 200/204
Isky 9365 Plus springs 235/560
Manley 2.15/1.60 SS valves
Trend 3/8"- 5/16"double taper pushrods
Brodix 1809 HVH intake fully ported plenum and runners
Holley 1050 HP Dominator
MSD billet dist.
NGK R5671A-8 plugs, .035" gap
Accell 300+ race wires
Lemons 2" tube headers

The cam is less than ideal, but did push a similar (4.155 x 4.125) combo with Brodix -10 heads to a 10.28@132 in a 3710 lb car on a spinning 1.49 60' (DOTs).

Here is the catch. The heads are Brodix 18X castings that have considerable time in them. Measured minimum cross section is 2.66 sq. in. The minimum cross section is at the pushrod pinch. I did go through on 3 ports trying to push it out as far as I could. 2.15/1.60 valves. Final measured intake runner size is 258 cc. 63 cc chambers.

I originally purchased the heads as I did not want to move to shaft rockers at the time. It turned out the rocker geometry was so bad and the pushrods interfered with the intake runners, that I ended up going to shaft rockers after all. Negating the whole reason of using the 18X compromise casting in the first place. Live, learn, and suffer the consequences. Too late to turn back now.

Current flow numbers after porting. 4.185" bore, 28" H2O depression. Reher-Morrison SF600 bench. No pipe on exhaust

.......Intake/exhaust
.200 - 144 / 127
.300 - 203 / 175
.400 - 261 / 216
.500 - 306 / 233
.600 - 334 / 240
.700 - 351 / 245
.800 - 359 / 248


Next year on freshen up, I plan to weld up and move out the pushrod pinch to 2.94 sq. in +. Basically greater than the current 90% throat area of the 2.15" valve.

Peak TQ occured from 5200-5500 rpm. Peak HP occured at 6300 RPM. Power only fell off by 5 HP at 6700 RPM.

Optimal timing was determined to be 35 degrees. Jetting was 82/83 with power valves front and rear. A/F ratio was not dialed in completely on the dyno and was 12.1-12.3:1 on the best pull.

After getting the engine home from the dyn0, dissappointed with the results, I contacted Jay Allen at Camshaft Innovations about a new cam. Jay felt like there were valvetrain stability issues with the current cam and springs and that there was good power left just going to an adequate spring. Isky said I've got enough spring as is. Upon inspection, there is evidence that the valves are rotating (float/bounce??). I have not checked the lifters for signs of control issues there. On EA3.2 Plus, Jays cam shows AVG. TQ up 20 lb-ft and AVG. HP up 24 HP. I received the cam Friday and likely won't have the chance to redyno. Will likely put the car on the chassis dyno though.

Before I post the embarassing dyno numbers, let's hear what you guys would expect and what you are doing with big inch SBCs with standard 18 degree heads. Again any combination specifics would be appreciated.

BTW this engine is going in a 35-3600 lb footbrake bracket car.

Those that know the results, don't let the cat out of the bag just yet.

Thanks,

Jason

[Jason G]

I have a pretty good idea of what needs to be done to fix my deal.

Surely some of you guys have built some big inch SBCs with 18 degree heads???

Any dyno numbers? Cam? Head data?

Thanks,

Jason

[RGL]

i dont know much about these sbc combos but ..... since you bought shaft rockers, seems like your throwing away about 15-20HP with a 1.6 ratio . i would have went with a 1.8 on the intake right off the bat , it costs the same money.

[Rick360]

Mine is more of a medium inch sbc. but since not a lot of others jumping in I'll throw this in. Here's a engine I built quite a few years back.

360ci, 4.060"x3.48", 18* dart heads, 2.15"x 1.60" valves.
Heads and manifold ported by me 8yrs ago. Flow numbers similar to yours, mine was about 10 more on exhaust.
18* Bowtie manifold w/adapter to Dominator.
15:1 compression. cam 282/295 @.050 114lsa and .770"lift w 1.7/1.65 rockers.

Dynoed 757hp@8000 and 522tq@7000 @ Patterson Racing.
Later put a better manifold on and gained .05 ET in 1/8th.
For a best 1/8mile of 5.48 @125 in 2380lb car @ ~1200DA air.

Rick

[Jason G]

RGL,

I already had the cam and was planning on using 1.6 ratio stud mount rockers. When I went to mock-up for assy. the rocker geometry was WAY bad and pushrods were hitting. No more P-V room either.

Rick,

Thanks for the info. That is about the HP I was thinking. 730-750 HP @ 6800-7000 RPM.

It ended up 672 HP @ 6300 RPM. 616 lb-ft @ 5200 - 5500 RPM. TQ is in the neighborhood of what I expected. HP is very disappointing.

The new cam has considerably less duration, but .753" net lift. EA3.2 shows adding about 20 lb-ft and 24 HP avg. Better, but still lackluster for what it is.

Thanks,

Jason

[Fatman]

Jason

I think you have to find out why this thing stopped at 6300.

I think the heads min cross section should support around 6900 given that the rest of the port is OK. The airflow is also there.

Could that spring pressure with the stainless valve be stopping it? Any chance of changing springs and getting it back on the dyno? I'd hate to swap cams when it was just a spring issue.

How much smaller is the cam that Jay recommended?