IDI "What if..." Durability and build question

[kc0stp]

kc0stp, or anyone. Where can I learn more about these 6.9's that are making big power. Everything I have seen generally lumps the 6.9 and 7.3 together but the 6.9 is favored for its thicker cylinder walls. For the most part I have seen the IDI engines top at the 450 whp neighborhood and the limit does seem to be fuel or transmission. Are there 6.9 IDI's out there that are putting down significantly more than 450? Id love to see what they are breaking on the engines at the 600+ level.

The closest your going to get is Racin over on FTE but hes currently running around on a 90cc pump and going to be doing an engine rebuild here soon. That said the only one to break the 400whp (hypermax excluded) is NMB2 and hes now joining the fummins crowd after his tranny blew also for what its worth his pump was a one off that managed to hit around 200ccs on a pump specced for 180

 

[WisdomWarlord]

Let's remember that in this hypothetical build, the fuel supply is at double the "normal" DB2 levels, so this engine gets 180cc's of fuel any time we want it.
If we can feed the fuel, what do we get to break, in the engine, and what do we have to do not break it? Bedsides get oit of the throttle. The transmission and rest of the driveline is of course the next, but separate discussion.

 

[The Warden]

As for bottom end? Ours are quite similar to the PSD diesel engines, so whats the limit to those? Anyone? Then subtract a wee bit for safety and yer likely golden!

I don't have any firm numbers on what the bottom ends can and can't handle, but they are a potential weak point. I remember when Ken at DPS built his low-compression 6.9l for pulling, he blew the bottom end out on the first run. I don't remember how much power or boost he was making (all I remember for certain is that he had shaved the piston tops to get the compression down to the 17:1 range). I remember he was talking about adding a girdle to the bottom end, but I don't know if he actually got around to doing it or not...

FWIW...

 

[Wood]

this is getting frustrating, so much damn mixed information on these boards.

im in a similar boat as the OP, trying to get a plan to make reliable power out of an IDI, towing power for myself in particular. and all i keep reading is people saying yeah, stock HG and studs your good to 450. then got guys saying yeah bottom end will blow out when you drop cylinder pressure. *** are you talking about dude?

then people saying yeah the motor can pretty much hold anything you throw at it, we just cant get enough fuel in 'em, then another guy in the same board stating i wouldnt put your banks setup past 10 lbs... with studs 15....

15 lbs to 35 lbs is substantial jump, this is the range of numbers i have heard on a stock gasketed studded 7.3..

who do i believe?

 

[79jasper]

Comparing a banks, ats, hypermax turbo to a real high hp turbo is apple's to oranges.

They can't flow enough. Too much drive pressure. Even a stock 7.3 psd Turbo is better, which is good to like 4-500 hp on a 7.3 psd, IIRC.

 

[Wood]

i wasnt comparing the two.

im comparing the differences in safe boost levels people are stating with these motors, regardless of the turbo.

that also doesnt factor into how much the bottom end can simply handle. im wanting 250-300hp. want to know if this is done at 30lbs of boost or 15? real examples of this, i just see people himmin and haahhh'n saying yeah i wouldnt do this but id would do that.

then its stated someone is just making 400 with 200+ cc of fuel. but then we can supposedly make 250+ on a stock 90cc pump? that doesnt add up. just trying to learn here and want to get information straight.

 

['94IDITurbo7.3]

NMB2 never got remotely close to 450whp......I don't recall his last power number with his idi....

racin was mid to upper 300's with his BW turbo and RD4 injection pump.

There are ZERO DB2 IP's putting out 180cc of fuel...those pumps were the DB4's......those are proving to be the opposite of reliable right now just b/c of what is needed to get them to 180cc and the consequential stresses put on the pumps while running on the engine. It also seems that parts, at least the key parts, for the DB4's are no longer able to be had......that is not a 100% certainty though....

Racin is gonna be building a 6.9 in the very near future as his current engine is toast....he is going to be experimenting with a 110cc DB2 that he is going to be building himself.....not a third party builder. he is currently running an A3K turbo, will be running a cam of his, and will be running either a 90cc pump or the 110 pump if it goes well. he says that he is hoping for a solid RELIABLE 300 FUEL ONLY wheel hp out of that set up. Later on he is gonna go balls out on another idi and go for broke from what i read.

In my opinion, if you are after near stock reliability with a NICE added bump in horse power, you would be MUCH MUCH FARTHER ahead money wise(and engine wise imo) swapping in a p-pumped 12 valve cummins, a built auto(or manual if you like) and be done with it. WAY less money to get way more power in return...best bang for your buck kind of thing.

 

[88 Ford]

Well lets break this down, first build bit is double current fuel delivery of a turbo cal DB2 pump which would put you right around 180cc's at the proven ratio of roughly 2.2-2.6 hp to cc which puts you roughly at 450whp. Boost isn't a good thing, you can take any of the lame 3 up to 20+ psi but a better suited turbo at 10-15psi will make more power. The only way to get 60psi out of an idi is with a vastly wrong sized turbo (like say any of the big 3 with 180ccs fuel) where itll be very inefficient and loosing power compared to a proper turbo.

All that said at 450whp the stock bottom end would hold up and all the top end needs is head studs and a camshaft (might want to do valve springs while your at it). Frankly weve hit 450whp and no ones found the limit of the bottom end or arp head studs/stock head gasket. The problem we currently have in making power is fuel output where as all that's readily avalible is 90cc pumps (Bull moose, RD2-90) with a few experimental pumps hitting 110cc's. If you can get enough fuel the speculated limit of the bottom end (where you should start thinking about upgrading for a reliability standpoint but could probably take it with ease) is 500-550whp and no one knows on the headstuds/gasket as so far the big power guys have been using 6.9s

Yep. NMB2 did it and RacinNdrummin was close as well. Racin did his on a stock high mileage engine as well and they both hit right close to 40psi. There is no reason an IDI can't hold at 450hp. They are stout engines...

 

[88 Ford]

I don't have any firm numbers on what the bottom ends can and can't handle, but they are a potential weak point. I remember when Ken at DPS built his low-compression 6.9l for pulling, he blew the bottom end out on the first run. I don't remember how much power or boost he was making (all I remember for certain is that he had shaved the piston tops to get the compression down to the 17:1 range). I remember he was talking about adding a girdle to the bottom end, but I don't know if he actually got around to doing it or not...

FWIW...

You have to remember the kind of work Ken does though. Its not surprising at all that it blew. Lol

 

[kc0stp]

NMB2 never got remotely close to 450whp......I don't recall his last power number with his idi....

racin was mid to upper 300's with his BW turbo and RD4 injection pump.

There are ZERO DB2 IP's putting out 180cc of fuel...those pumps were the DB4's......those are proving to be the opposite of reliable right now just b/c of what is needed to get them to 180cc and the consequential stresses put on the pumps while running on the engine. It also seems that parts, at least the key parts, for the DB4's are no longer able to be had......that is not a 100% certainty though....

Racin is gonna be building a 6.9 in the very near future as his current engine is toast....he is going to be experimenting with a 110cc DB2 that he is going to be building himself.....not a third party builder. he is currently running an A3K turbo, will be running a cam of his, and will be running either a 90cc pump or the 110 pump if it goes well. he says that he is hoping for a solid RELIABLE 300 FUEL ONLY wheel hp out of that set up. Later on he is gonna go balls out on another idi and go for broke from what i read.

In my opinion, if you are after near stock reliability with a NICE added bump in horse power, you would be MUCH MUCH FARTHER ahead money wise(and engine wise imo) swapping in a p-pumped 12 valve cummins, a built auto(or manual if you like) and be done with it. WAY less money to get way more power in return...best bang for your buck kind of thing.

When the tranny finally blew he was north of 400whp, if I rember right it was right around 450 and that was at 5000' elevation. Racin was seeing high 300s out of a 150cc pump. I do agree that if your after big power currently at least a mechanical 12 valve is the way to go if nothing else but for the fact that its been run over and over again so is 100% tested vs breaking new ground. What the future holds for the IDI no one can truly say beyond the fact that if we ever get the fueling issue sorted out we could probably play with the big boys (at least in the 12 valve category) but its going to be a long expensive road to get there.

 

[88 Ford]

NMB2 never got remotely close to 450whp......I don't recall his last power number with his idi....racin was mid to upper 300's with his BW turbo and RD4 injection pump.There are ZERO DB2 IP's putting out 180cc of fuel...those pumps were the DB4's......those are proving to be the opposite of reliable right now just b/c of what is needed to get them to 180cc and the consequential stresses put on the pumps while running on the engine. It also seems that parts, at least the key parts, for the DB4's are no longer able to be had......that is not a 100% certainty though....Racin is gonna be building a 6.9 in the very near future as his current engine is toast....he is going to be experimenting with a 110cc DB2 that he is going to be building himself.....not a third party builder. he is currently running an A3K turbo, will be running a cam of his, and will be running either a 90cc pump or the 110 pump if it goes well. he says that he is hoping for a solid RELIABLE 300 FUEL ONLY wheel hp out of that set up. Later on he is gonna go balls out on another idi and go for broke from what i read.In my opinion, if you are after near stock reliability with a NICE added bump in horse power, you would be MUCH MUCH FARTHER ahead money wise(and engine wise imo) swapping in a p-pumped 12 valve cummins, a built auto(or manual if you like) and be done with it. WAY less money to get way more power in return...best bang for your buck kind of thing.

Justin was easily close to 450hp or over it with his 200cc pump. He never dynoed it of course but even low balling power estimates at 2.2whp per cc and you will get about 440hp. So it is relatively easy to assume that he was at least close to 450whp. Also given that these pumps will be able to not break when the necessary corrections are made I believe we will soon see a dyno proven 400hp. Xcite over at FTE has a Db4 and will max it once again when the pump issues are corrected and Bronco78idi will also be in that territory when he gets the fuel as well. He is going to run compounds on his build and also has custom roller rockers as well from Harland-Sharpe. He has got some cash into that build.

 

[79jasper]

i wasnt comparing the two.

im comparing the differences in safe boost levels people are stating with these motors, regardless of the turbo.

that also doesnt factor into how much the bottom end can simply handle. im wanting 250-300hp. want to know if this is done at 30lbs of boost or 15?

You're not understanding me man.
Psi doesn't mean much, unless you're talking drive pressure. It's about the cfm.

Hopefully someone else can explain it for you.

 

[88 Ford]

Yep. Psi is just a measure of restriction. It is about cfm like 79Jasper said and how efficient it gets in and out of the engine...

 

[Wood]

You're not understanding me man.
Psi doesn't mean much, unless you're talking drive pressure. It's about the cfm.

Hopefully someone else can explain it for you.

okay i gotcha. sorry guys wasnt trying to be snoody. just new and confused. ill try to keep to reading like i have been.

i understand that different turbos are going to act different ways at the same boost level. i was just trying to say that i have heard "safe" numbers all across the board. just wanna know what these engines are capable of in a realistic stance.

 

[Wood]

NMB2 never got remotely close to 450whp......I don't recall his last power number with his idi....

racin was mid to upper 300's with his BW turbo and RD4 injection pump.

There are ZERO DB2 IP's putting out 180cc of fuel...those pumps were the DB4's......those are proving to be the opposite of reliable right now just b/c of what is needed to get them to 180cc and the consequential stresses put on the pumps while running on the engine. It also seems that parts, at least the key parts, for the DB4's are no longer able to be had......that is not a 100% certainty though....

Racin is gonna be building a 6.9 in the very near future as his current engine is toast....he is going to be experimenting with a 110cc DB2 that he is going to be building himself.....not a third party builder. he is currently running an A3K turbo, will be running a cam of his, and will be running either a 90cc pump or the 110 pump if it goes well. he says that he is hoping for a solid RELIABLE 300 FUEL ONLY wheel hp out of that set up. Later on he is gonna go balls out on another idi and go for broke from what i read.

In my opinion, if you are after near stock reliability with a NICE added bump in horse power, you would be MUCH MUCH FARTHER ahead money wise(and engine wise imo) swapping in a p-pumped 12 valve cummins, a built auto(or manual if you like) and be done with it. WAY less money to get way more power in return...best bang for your buck kind of thing.

cheapest i can find a 12v for around here is like 3k. my dad and i have a machine shop and my dad works full time for another as the engine assembler. he can get 12v cores but they still arent cheap. few hundred bucks PLUS whatever was wrong with the core (rod, piston, cam etc) to rebuild that. then source a trans or adapter plates. then do the work of actually putting it in, hooking up vacuum stuff for brakes, swapping PS fittings. its not as EASY as building a somewhat stout IDI and just putting it in.