rebuild hp numbers

[balljoint]

Whats the highest peak hp one can expect from a LEGAL 'blueprint' rebuild? On a 604

[rubbinsracin]

To add on to that, what is the cost people are paying to have a completely legal rebuild?

[trent1041]

By the number there are certified builders that charge from the normal low in of 1800 all the way to 6500. Yes 6500 I had a legal nesmith builder tell me that witch is a load of crap because it's not like they are replacing any main components. But the going rate is suppose to be 1800.

Now to the power side the legal rebuild usually is about 425-440hp and bout same tourqe on the older motors but the 2010 2011 2012 are a little better out of the box that good builders are getting low 450s on gas. The quickest power is VPs chp or ratman by renegade witch is worth about 10hp but it's about 10$ a gallon.

[dynoman14]

There are different rules for differing sanctioning bodies. UMP, Ne-Smith and Fastrak. They all have different sealing systems with UMP not requiring any. From one to the other there can be as much as 25HP difference as NeSmith rules allow a couple changes from GM Spec that Fastrak does not
( rings and bearings being the main differences ).

As far as costs involved, it depends on what you consider in your rebuild. You can go to GMPP.com and look up any of the stock parts and find out cam&lifters about $750, rods $350, Pistons $600, rings $250, bearings about $100, gasket set about $100. Springs, retainers and locks $125, valve seats $500 installed ( I have not seen a used set of heads yet without some cracked seats ). That is why a lot of second rebuilds drop valves or seats because they were not replaced on the first go round.

Total all that up and it is about $3K. And that does not include any machine work like block decking, honing, head surfacing or valve job, rod bolts and rod re-sizing. I know there are folks out there that will do it for less, and say that the extra work is not needed and can scrounge up some parts for less but like any other race engine you get what you pay for.

Anybody that says crate engines don't need the extra work has not measured up the parts and closely inspected them. For $5K they are an awesome engine but just remember what you are getting a Stock GM Replacement engine using HD Truck parts, Steel crank, PM Rods and Valve seats & Cast HT Pistons. Pretty good for a 400hp Factory engine.

As nobody has commented much on HP numbers here is a small part of what I have found since 2002;
I have a stock GM bolted 604 in my chassis dyno car from 2002-2003 era, never been re-built and it has 10,000+ pulls on it over 10 years and I change the valve springs and oil on it every month and the rockers every year. It started out at 367RWHP and with proper break-in 389RWHP ( +22HP ) and our Oil -v- mobil 1 we went to 402RWHP ( +13HP). With changes to our treated springs, retainers and locks we moved to 421rwhp ( +19HP+500rpm ). Changing to low drag WP, Alt, PS and Serpentine 434rwhp ( +13HP ). Changed headers a couple times and decided on the Coated Dyna-Tech Tri-Y header ( pavement ) 441RWHP ( +7 ). We are working with Joe Beyea to achieve similar results and have made some major gains in the last 2 years with our "In-House" customers seeing +15-18HP lap change on a header swap. With carb changes to dirt style carbs over Holley 650HP Pavement carb we have picked up to 467RWHP ( +26RWHP ).

These are all numbers on my Superflow Inertia Chassis Dyno over a 10 year period on crates and 25+ years on Supers, ARCA, BGN CTS and Nascar Late-Models. They are not for comparison purposes to other dyno's but more to show what can be achieved with a lot of hard work and attention to detail. Took an engine to a customer and ran on Willy's Superflow chassis dyno and the numbers were within 2% of my Superflow numbers, so if you have ever run your stuff on his dyno it will be similar to mine.

Engine numbers and parts swap numbers have been confirmed on multiple customer tests as well as outside engine builder dyno's ( Jeff Dorton, Darrell Gabriel, Johnny Pruitt, Ron Hutter, Katech, RCR, JGR, KBM... ). Parts run by Royce Bray and Bobby Dauderman in multiple Championship winning seasons as well as 100's of other 4m members.

Plenty of folks out there bash my numbers and ideas, but I am providing information that has been gathered over 10 years and 1000+ crate customers on the Chassis Dyno and 2500+ Pave & Dirt customers running my stuff.

Special thanks to all the folks that run my parts and run on my chassis dyno, most of them are happy enough to keep their gains & advantagea to themselves. I have tested customer developed parts and have 20-30 of them with their own special ideas that are making great power and it is still their Idea as their research on the chassis dyno is kept confidential.

That is how I have been running it for 25+ years and if I make it another 25, I guess I'll be happy.

Our big HP gains recently have been in Engine Acceleration with work in voltage supply and regulation, distributor curving and reduction of timing loss, mapping carbs for the fuel you run in your race engine, & mapping the timing curve, fuel curve, and fuel burn curve to the acceleration curve of a 604 crate. Each of these areas on their own is about 10 RWHP and combined it is 25-30 RWHP.

One thing to think about... Crate engine #1 makes 450HP and pull the dyno to max pull in 10 seconds...Crate engine number 2 has 450HP and the same exact dyno sheet but pulls to maximum in 8.5 seconds.

How and why does this take place???

Once more folks out there get Inertia Engine dynos you will see engine acceleration numbers discussed in more detail.