Precision engine 351 to 427 build up

[madmaxx]

The attached link details the build of a 351w based Dart block to 427. This is a direct comparison IMHO to the Roush 427 or Keith Craft 427. They finally dynoed it. There are 6 parts beginning with the intial block maching and demonstrates the attention to detail for sucessfull build.

As you will read in the dyno, they did not pick the optimium cam or carb for intial dyno. WOW, professional engine builders struggling with a cam selection, I dont stand a chance. They originally thought 600 hp and ended up with 515hp. I dont think they would realize the gaiin going from the first lunatti cam going to the second. Mine cam falls inbetween the two and my dyno numbers compared to his are 2ft-lbs away and 1 hp. I think they would have to get the custom grind.

According to his springs he is running 360lb open, to go with the larger cam I am sure this would have to increase spring pressure and bang we are back into stressing the valve train and affecting long term reliability.

I do like the distributor not requiring an MSD box, why dont we all use this? Any downside? I have no idea why he went with a bronze gear, they make the everwear for the distributor. Maybe he does not know as much as I thought he did LOL!!


http://www.precisionenginetech.com/p...-the-dyno-run/

[madmaxx]

You will also notice above 4K rpm the oil pressure only increases 2.5 psig, this verifies what Melling told me about oil pressure levels out above 4K rpm. His oil pressure was just below 60 psig but he was using straight 30W which is more like a 10W40 viscosity. Its amazing how close his dyno sheet matches mine. Once again excellent read with all part numbers, torque values and clearances.

[blykins]

For some reason the link doesn't work.

Engine builders don't struggle with cam/carb selections....I knew from the previous articles on this engine that their cam selection was too small. This engine probably made a lot more torque than horsepower though, right?

For a hydraulic roller, 360 lbs open is fine. What's on the seat pressure is more important.

[blykins]

Got the link to work.

It all depends on how well the heads perform. He'll need a lot more cam than either one of his "prospective" cams if he's wanting to get from 510 to 600.

I will say this: dynos have a lot to do with the results. A lot of engine builders have happy dynos...numbers sell engines.

[madmaxx]

Why is seat pressure important? It would seam that the open pressure would cause the valve train wear. I am pretty confident if he went with either of the next two larger cams he would float the valves unless he increased valve spring pressures or kept it below 5500 rpm's. I dont think he could ever get 600 hp, heads say max valve open is 600 where the one cam is above that.

[madmaxx]

Torque and horsepower were about the same 514hp, 520 torque. I would easily trade horsepower for torque, for example, 575 lbs of torque and 450 horsepower would make me happy as compared to 525 hp and 500 torque

[blykins]

Originally Posted by madmaxx

Why is seat pressure important? It would seam that the open pressure would cause the valve train wear. I am pretty confident if he went with either of the next two larger cams he would float the valves unless he increased valve spring pressures or kept it below 5500 rpm's. I dont think he could ever get 600 hp, heads say max valve open is 600 where the one cam is above that.

Seat pressure is what shuts the valves....thus keeping the valves from hanging open (floating the valves). 360-375 is adequate open pressure and I like to run around 150 for seat pressure on hydraulic roller cams.

I didn't notice what his seat pressure was....

I hope that he either bought the heads bare and assembled them, or bought them assembled and completely tore them down to check all the parts. If he did either one, he would know if he had room for a larger lift camshaft.

Some of the TFS heads make quite a bit of power. The TW-R heads will flow with a little work. They are advertised to flow 340cfm but the last batch I had flowed about 320. They took a little work to get them back up to their rated flow rate.

[Barry_R]

Mike - the guy who wrote the article - is a really good guy. The 600HP target was never going to happen with that combination of parts. I have a lot of experience floggin' middle 400 inch pump gas stuff on the dyno.

I have to agree with the cam comments - hitting 600 at that displacement is nearly impossible with that small of a stick. Getting the engine to peak at around 6500 would help, but that requires durations over 240 @.050. Its also on the edge with non-trick hydraulic rollers, which tend to get squiggly after 6200 or so...

The carb size comments are right on - I've seen a 17HP gain going from a 750 to an 850 on a 547 horsepower 445 inche FE with no other changes. He was also being pretty safe/timid in tuning looking at the BSFC data. Was in the mid/hi 400s where a serious piece will often drop into the .380s. I'd love to see the O2 trace on that - maybe something was off in the flow meter data.

They also insisted on calling the PowerJection a Projection. I think the former is the Chinese one, while the latter would be a Holley item. Either wway they proved that TBI systems still suck.

[Keithc8]

We do quite a few 427SBF with about 10.5 to 1 compression, hydraulic roller camshaft in the 246 to 260 duration range @ .050 with about .560 to about .600 lift. We use a AFR 205 or our KC Signature 195/210 heads with a Victor JR and they make 575 to 600HP quite regulary.
These engines are a complete process of machine work and parts. There is a reason why some of us own 2 million in machinery to have the best CNC equipment, best Sunnen 50,000.00 cylinder hone to get the cylinders with in .0005 of roundness and straightness. What is the deck heights on the engine, what are the ring gaps, what rings are you using, what are the bearing clearances, how is the camshaft installed and on and on. Our blocks are blue printed which means the bores are in the right bore spacing location and are 45 degres to the center of the camshaft and crank center line. Just way more stuff than most people understand and it is all done to each engine and these are just a few things that make some of these engines make more HP than some of the other stuff you see. The heads work is also something that most shops have no clue about. They do not even own a flow bench or test different valve jobs for flow or port designs.
If it was easy everybody would do it and with engines about everyone tries. There are certain things that I do not do because I know that there are better poeple that are qualified to do the job. I am not going to try and do brain surgery on my child or build a missile. Now there are a lot of things that I can do but do not have the time to do them and I do better working and making money doing what I know how to do and then pay them to do the other stuff and it works out for everybody.
Good luck with that engine stuff it is a pain it the ass, I should know I have been at for about 30 years now.

Keith Craft

[Dangerous Doug]

Even as a total do-it-yourself guy, one thing I recognize is that it is less expensive to buy a crate engine from a professional than to build one up myself. Unless you have a particular need for something specific, I'd say, "Leave it to the Pro's."

DD

[madmaxx]

That is the understatement of YEAR!!!!!!! No shadetree mechanic can compete with a KC etc. Keith has a problem, he likes to build the engine right so he doesnt have to do warranty work, and then he has the nerve to actually have a person answer the phone when you call. What is the deal with him, where is the $9.00 tech, the answering machine, the "we have never seen that before"

Originally Posted by Dangerous Doug

Even as a total do-it-yourself guy, one thing I recognize is that it is less expensive to buy a crate engine from a professional than to build one up myself. Unless you have a particular need for something specific, I'd say, "Leave it to the Pro's."

DD