herbdon
thanks for the good report on sparks, we've been needing just that kind of feedback, any idea on how much hp's you are getting? how about some of those CT motors, not hearing much from them, anyone?

 

Im all for a faster suv!!!!![img]i/expressions/face-icon-small-tongue.gif[/img]

 

Tommm,

Concerning your post that we are all pissed because we bought or built 690's and 720's and that now somebody has a "good reliable" 770, consider the following:


The 771cc engine is made by using a 105mm piston, a 89mm stroke (+5mm stroke). Assuming that we are talking a stock 5.374 rod length, at 8500 rpm, your piston will travel 8211.9 feet per minute. I would be thinking of a Kevlar ball protector at about 6000 fpm, especially with a stock rod. You could install a long rod to help with some of the problems you will encounter but it is no miracle pill.
Remember, the 105 piston is forged and weighs more than stock. Even if you run a good rod, 8200fpm is a very nasty thought. I am not saying that it will not work -- I just think you should reconsider your statement that it is a good reliable engine.

 

Dang, finaly got through this thread. LOL. Some good info and some dribble. The dyno was denied the race was excepted. Do it and post. Please.

 

does the Raptor have a good head/cylinder design in terms of sealing compression - 6 head bolts, etc?

I may be beyond what the ds650 head/cylinder design can seal with only 4 head bolts. If so then this is the limiting factor in terms of max power I can get out of the motor.

I'm going to add a second O-ring as a final attempt to keep the head sealed.

ds650 head

ds650 cylinder

 

Raptor720,

In all honesty I am not all that familiar with the smaller motors. I know a little something about old Ford's FE 390's and 289's.

Some of your responses I stand corrected on. Yes, there are thousands of ways to build motors and I did not take into consideration all of the various components. I assumed that for the price that some builders will use off the shelf parts. That would exclude the custom pistons with custom ring locations, custom valves, etc., etc. Although I’m sure you don’t need me to validate what you know.

In regards to the carbs, I still disagree; if you are going with a standard FCR of course they will need to be jetted for the application that follows my thought of it's all in the tune of the motor.

Port work – As I stated I know a little about V-8 and it would depend on where you want the power, longer runners, cc of runners, etc, etc.. So the unless you are welding and relocating valves and spark plugs there is a finite amount that you can do to a stock head.

As a Final thought, most of these “KITS” cost about the same. It’s my understanding that most of the little custom mods will not be part of a kit build. If I added up the cost of off the shelf parts plus a little money for labor I could get close to what some of the builders will offer. I don’t know what the profit margins are of these parts but I’m sure that it cannot be absorbed into the custom cam grinds, custom piston, custom head work, custom crank grind, etc., etc. I’m basing this on my 400EX when I was thinking about building it. I talked to Sparks, Trinity, CT, and a couple of smaller guys.

If you offer all of the custom parts in a KIT for the consumer at a reasonable price, you’ll be busy.

When it’s time for the cannon to go nuclear, Harry at Trinity will be first on my short list.

Not trying to start a fight just trying to clarify a misunderstanding.

Smitty

 

Hebdon- Thanks for chiming in, with your thoughts. Was the phone ringing off the wall at Powroll today? I believe that POWROLL taught mickey dunlop everything he knows.

Herbdon- Do you have any plans to have your machine dyno'ed? If and when i ever find a dyno within a 100 miles of the house, i will be there. I don't claim to have the most hp. I just want it for my own imfo, to verify that i have it tuned right.

POWROLL kit seemed awful cheap. I have a feeling you only get a bag of parts. The DW article said minor headwork?

 

Rap 720, are you guys seeing 8500 rpm from your built engines ?. When I was at Powroll shop last year the whole idea of the 770 was mega grunt without having to rev it's nuts off. Relistically do you guys see more than 7000 - 7500 rpm ?

Kiwi

 

I was somwhat suprized at the hp estimates on the poweroll 770 featured in the june dirtwheels (on the cover), estimated at 70 hp (though not dyno'd) is very similar to the output produced by 720 motors, however, the nitrous boost on that puppy estimated at an additional 24hp must make that awsome, they did a nice job of incorporating the notrous boost into the throttle (rather than switch) so it kicks in automatically at 3/4 throttle, what a rocket

 

On that 771cc congif, 6000 fpm piston acceleration is achieved at a mere 6200rpm. Now I know the stock 84mm stroke exceeds the magic 6000fpm number but the cast piston does not weight nearly as much. King's 686 tends to fall off at 7500rpm. Recently, I tested a 720 with FCR's and a cam of my own spec that continued to make good power to 9100rpm. 7000-7200rpm seems to be the shift point for hill racing the Raptor. I think I would have trouble short shifting at a substantially lower rpm. Who knows? I am sure there is an application for the kit but I will always question the reliability issue -- especially if you add N20!

I still like the hp numbers and performance of motors with a substantially shorter stroke. The Cannondale for one is about 20mm less stroke and it will run in the same ball park. Ever thought of a Raptor with a 80mm stroke?????

Smitty,

No offense taken. From the FE and little V motor comment, I can see you are a fellow Ford man.