RHS 410 update...

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Brian Hafliger

Brian Hafliger

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Ran the 410 again today. First pull it made 483HP and 515TQ so right where we left off. I'm now running hollow pushrods that oil up to the adjusters. Ends of the pushrods look brand new!
Bolted the 950HP on, and made 7HP more but it was a bit fat. So I stuck the 1" open spacer back on and leaned the carb out and made 493HP and 512TQ and moved the peak down from 5700 to 5500rpm. Avg TQ was down though...so it would have liked the carb leaned and no spacer. But time was short so I stuck the electric water pump on...absolutely no difference!
We did start with underdriven pulleys so from those to electric we saw almost no gain. TQ was up avg. .5.
So sitting at 493HP we decided to drop the water temp from 162 to 142. That netted us 500HP, and 528TQ and avg. for both was up over 10 for both HP and TQ!

So had I ran the electric water pump and 950HP on my car and kept the temp's down before my runs, I'd say it would have ran in the 6.80's and picked up maybe 1-2mph in the 1/8! Not bad for a 7K engine top to bottom that runs on pump puke and low maintenance.

I also over filled the pan by 1QT by accident and it lost 20HP immediately. Drained the 1QT and power came back! Ahhh the joys of dyno testing!!!!
Brian
 
It was nice talking with you yest. Brian, thanks for the advice! I can't beleive the HP lose from one Qt. of oil, even the difference the temps made.
 
Dang! When I read about those heads I KNEW they were going to be the hot new ticket... Well done Brian! When I get back from Afghanistan I should be able to afford a set of those :)
 
hmmm..you'd think the spacer would offset the leaning of the jets when you usually up the jets with a spacer, 'usually'.

Hows the distributor/time curve set on this thing?
 
pettybludart said:
What size tube on the hedders?Nice results with the RHS heads.
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last I heard they were 1 5/8 step to 1 3/4 tti..

I wonder what the heads flow with a carb bolt to the manifold.
head+intake+carb=cfm
interesting stuff.

and when engines make more power than the flow dictates, is it just that the variables have figured into the cfm/hp formula... or obscene volumetric efficiency, but with these heads?..
hmmm...
 
Are you thinking of trying the 2.05 intake OTB? on the stock X & J heads they are good usually for 4/5 cfm top to bottom.
 
I would like to see how these heads perform at their max porting capability...

And how in the heck did you get it to run 162 to 142 degrees? That's cold! Can those even be real world temperatures? Isn't normal like 180 to 200 when it's in the car??
 
Just out of curiosity, how much oil do you have in there? Is it a Milodon 7 qt pan with 8 quarts in it?
 
mopardude318 said:
I would like to see how these heads perform at their max porting capability...

And how in the heck did you get it to run 162 to 142 degrees? That's cold! Can those even be real world temperatures? Isn't normal like 180 to 200 when it's in the car??
Click to expand...

My car runs best around 120* at the starting line! (360/OEM heads)
Just gotta experiment and set the carb up accordingly.
But that's after the engine has been "heat soaked" - warmed up and cooled before going to the line.
If not careful, it will fall on its face.

Nice heads though! I've been keeping up with the latest on them.
 
That's really nice to hit the 500HP number. Good job with it.

I agree, with the cold temp/950hp combo it would have run a 6.8x at probably 98 or so. With the changes, that's a 23-25hp increase over the combo as run at the track.

Nice work!
 
Cold motors make more power, a long time ago GM engineers found an extra 5 HP just from reversing the water flow and putting the cold water into the top to keep the heads cooler. For bracket racing my motor ran the most consistant at 160 degrees.
 
The only time a larger valve is going to work is with porting. I know these come cut for 1.92 valves, but the bowls are large enough to feed the 2.02 valve. And since we blend the valve job, well they work like they should.
A 2.055 intake valve would steepen the short turn too much to help in any way unless you ported it.
I think with a roller cam and porting this could make an honest 530-540HP using the 950HP carb.

Installing a 1" open spacer on a dual plane intake leans the mixture quite a bit. When I bolted the 950 on, it was rich...like low 11's rich! After the spacer it was high 12's which was decent so I didn't touch it.
This was just a quickie dyno session before dis-assembly.
 
So in the CC build what all parts could you keep from the stock engine? Trying to figure out for myself just how low buck I think I could make it. I understand I might miss out on some power, but just curious. Can you reuse a stock oil pan or are there clearance issues with the stroker or something? Similarly, I assume you could reuse the stock ignition?
 
Map63Vette said:
So in the CC build what all parts could you keep from the stock engine? Trying to figure out for myself just how low buck I think I could make it. I understand I might miss out on some power, but just curious. Can you reuse a stock oil pan or are there clearance issues with the stroker or something? Similarly, I assume you could reuse the stock ignition?
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If you use a stock oil pan, make sure you use a windage tray. Stock ignition would be fine, just use a good coil.
You can literally use the stock top end, stock rods and a KB hyperutectic piston. This would be a very mild build but would add considerable TQ.
You could then use a larger cam like [email protected] to help move that power up the rpm range so it's not done by 4000rpm.
But you make like it done by then....LOL! I would not use a cam smaller than [email protected] though...even with really low compression.
 
mopardude318 said:
I would like to see how these heads perform at their max porting capability...

And how in the heck did you get it to run 162 to 142 degrees? That's cold! Can those even be real world temperatures? Isn't normal like 180 to 200 when it's in the car??
Click to expand...

I've had people argue with me on this forum that heat makes power. Let's face it, heat is energy, no doubt but to make good horsepower out of a an engine it should be cold. It does of course have to be jetted for that. I do the same as Myron, warm it up to 180, let it heat soak for 20 minutes or so then cool it down to 120-130 before a run. An electric water pump and fan with no thermostat allows you to regulate the temperature properly.
 
Heat in the combustion chamber makes power, heat in the intake manifold doesn't. As already said, every succesful bracket racer that I know personally that runs in the 10's likes to see 160 F when staging after the burnout.
 
so what you do before you run is, warm the car up to 180 then let the car sit till it cools too 140-160 then run it? and that wont hurt anything?
 
74Burntorange said:
so what you do before you run is, warm the car up to 180 then let the car sit till it cools too 140-160 then run it? and that wont hurt anything?
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Most guys run that way. I know I ran my duster at 140 at the burnout. Once the pistons are hot they're fine.
You want the oil hot and the water cold! Really for bracket cars you just want to be consistent and repiticious with whatever you do. Running cold allows a quicker cool down for the next run which helps a ton when hot lapping towards the end of a meet (if you make it that far)!
 
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