Performance engine parts

[FordGuy100]

Truth is I don't think you need to really harden anything beyond stock for 300Hp at the crank. I highly doubt my truck is making 250 at the crank and its already a bit of a handful when empty. When loaded, its "adequate".

So Justin, Russ's truck is really that much faster than yours?

Faster, I dont remember. I remember it having a really really smooth powerful lower end. It pulled harder than my truck does

 

[monkeyboi]

What percent is used for measure of loss through driveline on a chassis dyno?
Heath put up 185 on the DPS injectors which equates to 246 hp at the flywheel if 25% is used, but would it be less loss due to his manual? Or is 25% loss too low. Searching the net, it seems SAE says too many variables to even determine an estimate, but I have heard 20% for manual, 25% for manual and so on, and so on...

Won't spinning these engines higher kill mileage and lessen low end performance. There is always a trade-off, especially where cams are concerned, but I doubt 'best performance' was what determined the stock grind.

 

[FordGuy100]

Yeah I think 25% is a decent number, going through the transfer case as well, and turning fairly big tires, seems like a good number to use

 

[david85]

Pretty sure its around 30% but a lot of that can be right in the tires on the roller depending on what kind of dyno is being used. Less energy is lost on flat road vs a round roller against the tire (more sidewall flexing). At least thats what I heard. I also heard that SA did testing on differentials years ago and found them to be about 96% efficient. For transmission losses, maybe 20%? Probably less for a stick shift or non slip auto.

Yeah I guess 25% or 30% for something like a C6.

Front wheel drive cars are said to be around 20% loss for the stick shifters. Probably not far behind for the autos.

 

[ameristar1]

What percent is used for measure of loss through driveline on a chassis dyno?
Heath put up 185 on the DPS injectors which equates to 246 hp at the flywheel if 25% is used, but would it be less loss due to his manual? Or is 25% loss too low. Searching the net, it seems SAE says too many variables to even determine an estimate, but I have heard 20% for manual, 25% for manual and so on, and so on...

Won't spinning these engines higher kill mileage and lessen low end performance. There is always a trade-off, especially where cams are concerned, but I doubt 'best performance' was what determined the stock grind.

The cam from the factory is based on 30 plus year old technology and at best was just to make sure it ran and did not break. The modern designs offer much more, and if the package as a whole were more efficient, the fuel consumption would go down as power went up despite revving it higher. The area under the curve will be much stronger, so that you don't have to give it so much fuel to get the vehicle moving. We are still dealing with pretty large engines that have a lot of compression, so the trade off won't be as bad torque wise.

 

[Pearl_Diesel]

Well, what if we add propane into the equation? Throw on a grill bottle along with the turbo and cam? It won't net 70 horse, but 30 or so maybe, I don't exactly know how well propane acts on an IDI

 

[Pearl_Diesel]

I'm still of the notion that High RPM's aren't the key here, just proper tuning and parts. No need to take overbuilt stock parts and beef them up for a conservative horsepower build anyways. I mean, if you were trying to shoot for 800 or more, yeah, It wouldn't be a bad idea to have it balanced, cryo treated, etc. But for just a street build, what's the point?

 

[ameristar1]

I agree with you, but there should be enough scope in the build so if someone wants to go there, they can. A street motor will be done by the stock governor cutoff point, which is around 3300-3800 rpms, but if someone were to put a higher rpm spring in the pump, the motor won't lay down. You're just tapping into the higher hp. But at the same time, there's enough power under the curve that if you want to lug around at 1500-1700 rpms you can. That's the way the Cummins motor is set up. That thing has enough strength and cam that it can be rated at 160 and still hit 800-1000hp without necessarily changing the cam timing.

 

[f-two-fiddy]

Cryo treating is out range, price wise, of just about everyone here.

Besides, from reading IDI message boards for 7-8 years, I've only heard of 2 crank failures. One was coolant related, the other was posted here. I can't remember what the determination was.

I'm pretty sure the stock bottom end is plenty stout for anything we're going to throw at it. Heck, Dave Sponagle has had his stock crank running over 20PSI for over a year. And He's not running around ***** footing it.

 

[ameristar1]

Cryotreating is not that expensive. 300 Below Cryo can do the crank for 150.00.

 

[hesutton]

Not do be Johnny Downer, but I really fear the cam thing will be a dead end street. With the IDI engine design needing such a high compression ratio, there simply is not enough clearence for much more lift or duration. I hope I'm wrong, but the physics are what they are. With lower compression (19 or 18:1) you will need much more boost that can effeicently be provided by a Banks, ATS, or Hypermax IDI turbo. Then you have cold start issues. It may be quite expensive and difficult to attain 300 reliable HP at the rear tires. Even more so in a streetable truck.

Again, I hope I'm wrong, but the IDI was designed by IH for one purpose, to work for hundreds of thousands of miles without failure. Not to make 300HP reliably. Maybe we are asking too much from it? Time and money will tell.

Just my $0.02.

Heath

 

[ameristar1]

Fear and failure are not an option here. We're hot rodders, doing things like this is our stock and trade. Figure out the problem, and fix it. This is what we do. You gotta think out of the box if this engine is to perform.

Look at it this way. Do you still want to play with something that can't break 1 hp/ci, even though everything about it says it can? It has the heads, it has a strong bottom end, but it still needs help. We are going to get this sorted out, and it won't take a million dollars to do it.

I'll give you another incentive. The 6.2/6.5 GM diesel, which everyone says is a pooch, is now gaining in popularity because it can be made to run and run hard. Same IDI style format, same injection system. Except Heath Diesel is going almost 160 mph in a street driven full size truck with one (a 6.5) and getting great mileage to boot. I keep in contact with them, they recently put together a 6.2 to run this year, and expect to go FASTER with the smaller motor. Stock heads, block, cam, rockers, and a DS4 pump on top of that ( off the shelf, unmodified ).

The 6.9/7.3 has what it takes. Wouldn't be nice if instead of contemplating a swap just to get 350-375hp, you could keep what you have and get the job done?

I don't think we are asking too much of the IDI; we haven't been asking enough.

 

[sootman73]

can we look at the cam in the 6.5l engine? its nearly identical to ours with idi injection and what not but my friends can run circles around me with only $1500 invested in the motor(stock pump and injectors and turbo)!

there has to be something significantly different with those motors for them to be able to run like that and we cant even get to 300 hp? have you seen some of the videos on youtube of 6.5ls? i want that.

i was thinking the timing and what not of those motors could really get us a headstart...?

 

[FordGuy100]

I brought up the timing idea. I know my truck is much stronger with the advance timing. And if your suck air in your IP and it increases the advance dramtically, its like you hit a nitrous switch. Supposidly it eats glow plugs. I think with such high compression, you cant run all the much timing, but if you drop compression some, I would expect you can run more timing. Almost in a linear equation. If we run 9.5* timing with 21:1 compression that means if we drop to 20:1 we should be able to run 10-10.5* advance timing, just a rough guess. Heck it might even be a little more.

What do the 6.5 guys do for power? We have the same basic engine design, we should try to follow suit some....

 

[ameristar1]

It's the combination of cam and pump timing that makes the 6.2/6.5 run like they do. Looking at the power curves of both engines, the GM has a broader power curve than the 6.9/7.3, even though it does not make as much power.

It's all in the combination, and the GM is better matched for performance use.