6.9, 7.3 N/A, or 7.3 IDIT long block for hi-po build

[kas83]

With a lot of talk and speculation as of late as to how these motor will hold together, which platform do you think would be best to base a high performance motor on? Will worry about fueling later, need to have a sturdy base to build off of.

A 4000 rpm, 350 rwhp, ~20 psi buildup that would be streetable, easy starting, and reliable. Thinking of 20:1 or so on the compression side of things if it would hold together. This compression ratio with the boost figure mentioned would be breaking new ground, but I feel it could be done. I don't wanna hear anyone saying there's no reason for turning them that high, or anything like that. I'm talking a serious build for someone that wants a good daily driver, fun time weekend sled puller, quick street truck, so forth. Cummins swap is out of the question, must stay V8 IDI for posterity.

These motors generate good torque, but I feel the extra RPM will be needed to reach the 350 HP goal.

This is a discussion thread, the motor will not be built for a while, if at all, as I'm out of work, getting married and have a baby on the way. But in the meantime, I'd like to brainstorm what it would take to get one of these motors to make power, hold together, and stay driveable. I've read of an IDI dyno'd at 289 rwhp, which equates to roughly 360 at the flywheel, so I don't feel the 350 rwhp goal is too far off. So let's hear it.

And before anyone asks, this comes from building two CTD's over 400 rwhp, one of which is now a 6k rpm, twin-turbo, 800+ rwhp sled puller, and not being able to leave well enough alone.

 

[dyoung14]

I am comming to beilieve that the bottom end is solid at my 4000+ rpm, in my build im just going to stud the rods and main caps, but the valve train needs a little work, along with a few other things

 

[Goofyexponent]

I know you said you didn't want to hear it, but why turn it up RPM side of things and risk tearing it a new one big enough to drive a log truck through? There a way that LOTS more fuel could be put into the engine at a lower RPM than 3500 and still get the power you wanted to.

What about taking a 7.3 IDI-T block and rotating assembly, sleeving it down to a 6.9 bore (as mentioned lots before to eliminate the block worm issue) porting out the heads a little, both intake/exhaust runners AND the pre cup to improve a little more flow, while lowering the compression a bit, then running compounded turbos, moose pump + injectors, BIG @$$ intercooler, custom ground cam, slightly shaved 6.9 aftermarket pistons, studs everywhere, electric water pump and cooling fans to free up some HP, propane injection (nothing too crazy now!) and advancing the timing a touch too much for the GP's to handle (although there goes the easy starting out the window, because you will have to eliminate the GP's to run more timing)

 

[Agnem]

How come the only people who want to dream, are the ones without the resources to make it a reality? Meanwhile, those with money have no time and are more realistic with what they want to do with that money. The reality of life I'm afraid. Your going to have to have serious coin to do what you want to do. Lots of custom work, including some major pump modifications. These injection pumps begin to defuel past 2700. The range of available motion for maintaining correct timing and the ability to get the fuel to the injectors in the milliseconds that remain from the stock port alignment are not sufficient to support any real fuel delivery at the RPM's your talking about without some additional and expensive modifications. Yea, you can spin it, but by then you have less fuel than you did 1000 RPM's ago.

 

[Goofyexponent]

Would a moose pump be able to do anything close to this, Mel? Or is there anything else that can be sone to add to the fuel delivery capacities of a moose pump and injectors?

Might be a market for them in the sled pulling and drag racing industry lol. Never thought I'd say drag racing referring to an IDI lol

 

[DeepRoots]

I've yet to run out of fuel with a moose pump.
I'm barely able to use half of the fuel available at any reasonable rpm.

Just food for thought, designing the engine to get power over 4000rpms may move the whole power range further up.
Getting more power at 4000rpms and loosing it up to 1500rpms seems like a bad trade to me.

 

[Goofyexponent]

It would be like a 2 stroke dirtbike then...Nothing down low, then all kinds of power up top where it wouldn't make a good daily driver.

I vote leaving the govener set to 3200....or right around there and see what can be done to add power. But it's your motor, and it would be interesting to see what comes out of this.

 

[hesutton]

Looking at all the dyno curves from the Rally dyno event, these engines peak HP is before 2800-2900 RPM. After 3000-3100, it falls on its face. Just food for thought.

Heath

 

[icanfixall]

Give a call to Barnett Performance... They offer a stroker motor and three differant stages of head porting. Someday I want to "see" how my port work compares to theirs. I know I put more work into mine with the polishing I do. A 7.3 block sleeved down to a 6.9 might get you what you want. A high hp daily driver on propane doesn't need to burn the gas all the time too. Water-methonel the same way too. Then add some nitros and you have some hp for the weekends.... Look at my build and figure out what you need from that.

 

[kas83]

How come the only people who want to dream, are the ones without the resources to make it a reality? Meanwhile, those with money have no time and are more realistic with what they want to do with that money. The reality of life I'm afraid. Your going to have to have serious coin to do what you want to do. Lots of custom work, including some major pump modifications. These injection pumps begin to defuel past 2700. The range of available motion for maintaining correct timing and the ability to get the fuel to the injectors in the milliseconds that remain from the stock port alignment are not sufficient to support any real fuel delivery at the RPM's your talking about without some additional and expensive modifications. Yea, you can spin it, but by then you have less fuel than you did 1000 RPM's ago.

The reality is that I'm sick of people automatically shooting other's ideas down. Everyone always says it won't work, and rarely offers proof. Fueling is not the issue right now, the motor setup is. There is no reason to worry about the fueling until there is a solid base established, or at least that's how I built my CTD's.

People with money being more realistic with what they want to do with the money? The IDI crowd is pretty sensible, but PSD owners throw tons of money at their trucks to get the power I'm looking for.

And are you saying that the only issue will be fueling to 4000?

Also, the minimal loss to lowend power will be fully negated by a quick spooling turbo, with a wastegate, and the mid range will be excellent.

And one last thing, Heath, stay out of it, you haven't had any useful information to add to this thread or any of Dyoung's. All you bring up is past setups, dyno figures, speculation of what you think won't work, but absolutely no proof that NEW and INNOVATIVE setups won't work.

This is breaking new ground for IDI performance, basically throwing everything out the window and starting fresh, which is what alot of people in diesel performance have done.

 

[seawalkersee]

I would not sleeve the 7.3 "down" to the 6.9 as someone suggested. I learned something yesterday about the way the diesels make their power. The larger the consumption number is, the more power it can make. Not compression, but you get the number by having the pressure at TDC divide by the pressure at BDC (or vice versa) which should be in the 12-15 range for stockers I believe. This number is greatly increased by the bore increase. Ask someone who now has a 7.3 who owned a 6.9 in the past.

I am not looking for huge power. I want something that can tow a trailer and get 20ish MPG. I plan on keeping the 9" rear and 44 front so too much torque will kill my setup. This is why I have the 6.9. As soon as I can get a set of the moosemeiser or whatever they are called (with the multi hole tips), I will be almost done with the drive train.

SWS

 

[hesutton]

And one last thing, Heath, stay out of it, you haven't had any useful information to add to this thread or any of Dyoung's. All you bring up is past setups, dyno figures, speculation of what you think won't work, but absolutely no proof that NEW and INNOVATIVE setups won't work.

Take my information or leave it........ that's up to you. If you only want maybe and what if's....... don't expect to get only that here as there are guys here who've worked on these IDI and other diesels for years. There will be positive and negative to any issue posted here.

I've only posted facts and real measures of IDI performance. If that shoots you or anyone else down, that's not my intent. But, trust me......... I'm done with posting any more information.

Put your money where your mouth is........ build something "new" and "innovative," dyno it, and share that information with the rest of us. Posting theory all the time gets us no where. Test it...... as you have zero data to support any of the claims listed above.

Heath

 

[SparkandFire]

I think what Mel is saying is that there are mechanical limits to the Stanadyne DB2 injection pump that hinders it's ability to pump adequate amounts of fuel at higher RPM's.

If I guy could come up with a different injection system for the IDI engine, then one could assume that those HP numbers are possible...

Remember, the high HP/Torque numbers on the PSD are from technologies such as High Pressure common rail injection, multi fire piezo electric injectors, computer control out the yin-yang...

If you want to bolt stuff like that up on an IDI, i'm sure you could twist driveshafts and blow out Sterling axles like no one's business, but from what I gather from my short time on this forum, the guys here are all about reliability, ease of maintenance and repair, and keeping to the form of what Ford and International developed these trucks to do...

I respect that.

Just my two-cents...

 

[icanfixall]

Sorry to say this but there are no multi port injectors for the idi motor.. Thats really a sad point to... A little information about a 7.3 sleeved down to a 6.9... You nor I can tell the differance in end horse power.. Look it up and see what the 6.9 and 7.3 hp numbers are stock... Then look at the top fuel big motors compared to the small motors they run... The cubic inches are very small.... I'm not here telling others what not to do or try without some facts... I have all the information to back up whatever I post here. I will stand up when I have posted something that isn't correct. I will continue to learn too. I have made plenty of mistakes and those are posted here so others wont do what I have but... If you want to do what I did and made mistakes then go full bore and enjoy what happens... Some here love to see windows in blocks but remember this... These blocks are no longer made. Yes, you can buy new offshore 7.3 heads but you can't buy new 6.9 heads anywhere on the planet... Yet... I put a lot of time and engineering into what I built and all that information is free to anyone that wants it. Yes... I could sell what I know and make a nice income off it but I do this for everyone. Thats the simplest way I can say why lots of us are here helping others. For me its a way of life... Not a truck. Of all the members that have used my help at their homes I was only not able to start one members truck. I really felt bad for him too. I will continue to help those that want the help. We are here for the same reasons... No need to diss someones answers. You and I can agree to disagree on something...

 

[dyoung14]

ok my question is, somewere on the net i saw that the DB2 is capable of turning 5000+ rpm, so why can we only fuel to 2700? what cuases this to happen? why wont they supply all the way to 4500 or more, and im not tryin to start a fight or anything, but were the idi's on dyno sheets make peak power is with stock cam and most with stock ip, i think with a cam that will allow power at that rpm then a pump that can supply the fuel then we would see motor that would spin high and break our low power numbers