Pseudo racing engine surprise

[gmrocket]

hey guys,here is another example of a few guys who get the job done,my recent build is a 383 sbc dart heads titanium everything ,makes 532hp @ 6800rpm what a joke i have got nothing on you randy,i read posts from you,big joe and melway here in australia and i am not trying to piss in your pockets because what you guys do is give me motivation to try harder and look outside the box and that i thank you guys for.

I.dont want to make feel worse than you do.....but its probably much worse than you think. Your making 532@6800 and this thing is doing just about that at a much lowet rpm. This makes 512 ft lbs at 4800, 492 at 3500....ill bet your tq is know where near that!!

[randy331]

Randy, surely your not going to leave that thing in unported, unrefined form? Any plans for recamming or head or manifold work? Think that thing would run better in that rpm range with less exhaust duration?

At some point yes there will some ported heads/intake on Pseudo. (then it will be re-named) Won't happen this year, got too much to do right now. I gained work today in fact. I went to red lobster for lunch and when I got home there was a set of LS3 heads sitting at my house. Figured after I told that guy what I'd do on the LS3 heads he'd be running from my shop.

On the cam,...? the ex lobe on the pseudo cam is a solid roller lobe and it has a hyd roller lifter on it, so it has lots of seat duration on the ex side. But it still liked the 1.6 rocker on the ex over the 1.3 rockers and lost nothing at the bottom of the pull. When the cam was in 6* advanced it made a bit more at the bottom and the EVO at the seat would be 87* BBDC with the cam in that position. I may get some really odd cam for it to try, like a 240*/275* on 112* LSA. Be interesting to see that on the dyno. Track testing a cam like that won't tell me what it did to the bottom of the power curve. Then after porting the heads and intake it'd be interesting to see how different the results were between those 2 cams.

Randy

[CGT]

I went to red lobster for lunch and when I got home there was a set of LS3 heads sitting at my house. Figured after I told that guy what I'd do on the LS3 heads he'd be running from my shop.

That guy probably isnt quite right, he should probably anticipate smaller valves and epoxy

When the cam was in 6* advanced it made a bit more at the bottom and the EVO at the seat would be 87* BBDC with the cam in that position

Interesting, thats a very early EVO, but I am starting to see that trend here and there. Im sure there may be point where too early may hurt low speed power, but I suppose that point may not be as early as one may think. I know GM has headed that direction. Of course they have other considerations besides overall horsepower.

[OILEAKY]

Randy, how did it run with those 1.3 rockers ? Just curious......

[408 Nova]

Dang! The way your Nova runs makes me want to burn my car! I'm not much faster, with a what I think is alot more engine.

[randy331]

Randy, how did it run with those 1.3 rockers ? Just curious......

Below is the best pull made with each of the 3 rocker combinations we tested. We made at least 2 pulls with each combo.
Left column is 1.3 ex and 1.3 in
center column is 1.6 ex 1.3 in
right column is 1.6 ex 1.6 in

We didn't test 1.3 ex and 1.6 in. There's always more things to test and more questions at the end of every dyno session.

Code: Select all

  
 rpm	  1.3/1.3  1.6/1.3  1.6/1.6
3500		326		327		329
3600		337		335		334
3700		342		340		341
3800		349		350		350
3900		354		359		361
4000		364		371		370
4100		378		384		382
4200		390		394		395
4300		403		410		407
4400		412		422		423
4500		427		433		431
4600		436		444		444
4700		449		453		455
4800		456		462		463
4900		463		468		471
5000		466		474		475
5100		470		480		485
5200		481		484		489
5300		487		488		498
5400		483		498		504
5500		487		487		504
5600		492		504		511
5700		491		502		517
5800		494		506		521
5900		495		507		518
6000		492		502		524
6100		487		508		515
6200		487		506		515
6300		489		505		515
6400		481		503		517
6500		481		503		508
                                    

Dang! The way your Nova runs makes me want to burn my car! I'm not much faster, with a what I think is alot more engine.

That seems a little extreme !!!

Randy

[rewguy]

Did you measure the area at the PR? Just curious is all.

[jmarkaudio]

We did something similar about 20 years ago. Dish piston 406 on 93 pump gas, production vortec heads with only bowl cleanup and 1.94/1.50 valves, a large Crane FT hydraulic cam, SV intake and a Dominator, 2800 lb Malibu with a 4.30 gear and 32" tires. 10.60's all day long.

[F-BIRD'88]

A light weight race car is a nice thing. My simple 9.8:1 ported 062 vortec head hyd cam 406 would run very similar when
in a 2800 lb drag race car with race converter. Especially if changed to 11.4:1 and 100 octane.
The vortec heads work pretty good. And the Bowtie vortecs are even better.

A rocker arm ratio increase shows typical more power especially if/when the camshaft is small- under sized
for the purpose. If the cam is more correct duration to start with, the rocker ratio change
will show a lot less power gain. This cam is small for a racey motor..... so...

Nicely done stuff irregardless Randy331

[OILEAKY]

It's interesting that the horsepower gained from changing the 1.3 rockers to 1.6 ones, gaining about .110 more lift at the valves, only netted about 6% more HP @6500, and 2% at 5000 rpm. ( if my math is right !) Those are some good heads !

[fastblackracing]

Nice job on that engine combo Randy, you will surprise many with its performance. Question--what did the power numbers come in at with the 1.3 rockers? And have you considered some thicker trans oil for stall speed help? A lot of the turbo buick guys I know use the john deere hygaurd with good results. Seems like 200-300 tighter might be more on a 500HP build. Mannie Just saw the rocker post

[randy331]

Did you measure the area at the PR? Just curious is all.

No, it's whatever they are as GM sent them. My guess would be about 1.75" csa at pushrod, but I don't know for sure.

It's interesting that the horsepower gained from changing the 1.3 rockers to 1.6 ones, gaining about .110 more lift at the valves, only netted about 6% more HP @6500, and 2% at 5000 rpm. ( if my math is right !) Those are some good heads !

I thought the gain was a decent gain considering the heads are un-ported. The heads flow no more air at .600" lift than they do at .475" lift, so the only gain would be from time/area. Likely be different results with the heads ported, but know way to know for sure without testing it.

Randy

[CGT]

So lifting the valve into port stall on both sides netted power increases?

[cjperformance]

Excellent ! Less is often more.

[rewguy]

what hyd. roller lifters did you use?