Take a relativly stock reg cab Radix 5.3, on street tires vs our trucks.

We have seen some times posted, Now according to the almighty Cross state Track list our Times are better causing some to say B.S.!! how can a cammed 5.3 beat a SC 5.3???
The radix truck has alot more power but the stock truck is not set up to get it to the ground with the tranny not even sifting above 6000.

Now add evrything I have done to mine to a the radix truck and here comes mid 12's(Flyer) blowing mine away.

My times are a result of cool temps, good traction and low elevation.
Now throw in a very loose stall, 4.10's, 28" drag radials, caltracs, suspension, driveshaft, Tranny, cam and good exhaust.


I'm just glad to hit 13's without a radix
I will be really glad to hit 12's with one.

I'm looking forward to a dyno just to see whats going on. I dynoed it along time ago before all my mods and would like to see haow the pwerband has changed.

 

I really dont know why he feels that way. I think the stock heads flow pretty good for the bore size we have.

 

Get that sucker on a dyno.

 

My cam is not much different from theirs. 2* more intake duration, 2* less exhaust duration, a little more lift and a little tighter lsa. Using the online hp calculators and the mph from my last outing at the track I am guessing mine will put down ~330 on the rollers.
I will also agree with what Seeing Red Again said... It is hard to compare dyno numbers unless the vehicles are done on the same dyno on the same day. As for the great fluxuation of numbers mentioned earlier, there are lots of dyno tricks as well as dynos not set up correctly.

 

I dont know if this is Allan's reasoning but from doing my own, this is what I think. The valves are shrowded real bad on the 5.3 heads. I saw were the exhaust valves were acutally rubbing onthe heads in stock form. With our small bore it is hard to open up the combustion chambers to unshrowd the valves, even with our small 1.89/1.55 valves. So dont think it has anything to do with port flow (which is what you mostly gain on ported heads), it is getting the into the cylinder, passed the small bore, where the 4.8/5.3 falls short.

 

Can some1 explain valve shroading to me...

Thanks!

 

Man, this would be so much easier to explain in person... but I am going to try. Basicly it is when the valve is too close to the combustion chamber wall to allow air to flow from the port, over the valve and into the cc in that particular area, hence inhibbiting the entire flow area of the valve port.

 

02Reaper... you asked me in a PM about my last dyno sheet so here it is. This was with all the boltons and the '00 vette cam.

 

Yeah, but you also have to take into consideration, Allan uses a different lobe, faster ramps, different valve events, and given that, we still barely have a comparison.

But who knows. I think it'll be interesting one way or the other.

 

good info.

Yeah, the exhaust valve nearly touches the combustion chamber wall and the intake valve isn't far off.

I wish I knew the formula to figure out the cfm requirment given most of our operation rpm range. It would help.

Stock heads see a max of 226 in. & 174 ex. @ .600 lift