Do you have personal experience with this, or have you read that it will lift heads at that boost level?
Stroked 6.9
- Thread starter carsonlhammond
- Start date
Oledirtypearl86
Full Access Member
Iv been running pretty reliable on a 6.9 with a hypermax at 14 lbs for quite a few years now
Also had a customer who ran 22 intercooled psi through a 6.9 on overtorqued stock head bolts with a 110 and 60-1/P trim for two years..
03wr250f
Full Access Member
got a buddy who lifted heads on a 6.9 studded at 22psi intercooled on a banks charger.
got a idit engine that ran a R&D 110 stage 1 injectors and stage 1 drop in for 20k miles racing and driving as hard as possible seing 30 psi on 187k stock bolts
its a general rule that over 15ish psi on studs gets into dicey territory on a 6.9. It is not a law. same way over 15 on a 7.3 is dicey but not guaranteed to lift heads. because i ran my engine with **** intercooled to 18 psi for a year and a half and only tore it down to do head studs and a cam.
Engines respond differently to conditions. general rule/warning so a guy doesnt go for gold and get disappointed when he lifts a head thinking life will be roses and butterflys.
got a idit engine that ran a R&D 110 stage 1 injectors and stage 1 drop in for 20k miles racing and driving as hard as possible seing 30 psi on 187k stock bolts
its a general rule that over 15ish psi on studs gets into dicey territory on a 6.9. It is not a law. same way over 15 on a 7.3 is dicey but not guaranteed to lift heads. because i ran my engine with **** intercooled to 18 psi for a year and a half and only tore it down to do head studs and a cam.
Engines respond differently to conditions. general rule/warning so a guy doesnt go for gold and get disappointed when he lifts a head thinking life will be roses and butterflys.
Macrobb
Full Access Member
I got it up to 281RWHP recently! That's with S360, 110 IP, R&D cam(which I honestly think hurt my power more than made more - very little down low and it makes less boost than it did with stock) and stage 1 injectors.
(The same day, my friend with his 500k mile 97 Cali PSD and *just* a tuner made... 283. *sigh*).
Edit: Revised numbers down by 20RWHP. I mis-remembered them.
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Sweet Congrats! Is that the studded engine or the idit? Bummer to hear about the cam, I have been thinking about trying one in the race truck, I'd like to see the dyno graph that combo made.
They are a set of IDIT heads Im building with 6.9 precups, inconel exhaust valves and stainless intake valves with three angle valve job, light port/polish, opened coolant ports, comp 910-16 valve springs with 6.9 valve seals, manganese/bronze valve guides and a set of toolsteel retainers.
carsonlhammond
Full Access Member
With all due respect I am going to listen to Wes before anyone else. I think he has the most experience in pushing these engines to their limit. To me and I think a lot of other people on this forum we like to hear stories of experience and not just hearsay from “your uncle Jimmy’s buddy who pushed 17 psi and it done blew up”. I feel there was something wrong with assembly/manufacturing if it lifted the heads at 17 with studs. Wes has many times told about 6.9’s lasting extended periods of time under high pressures than that. Yes, you are always risking it putting boost to a 20+ year old engine but over-torqued studs WILL hold those heads down under that pressure...for awhile.
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Well I think any data is worth taking into consideration as long as it’s based on real world experiences and not opinions, that’s what you gotta wade through on the internet. I live in a certain environment, and maybe not everything that applies here is applicable to somewhere else, or vice versa.
Macrobb
Full Access Member
Studded 7.3 IDI, 88 or 89 model year block I think.
And, I misremembered my numbers. Was 20HP lower on both IDI and PSD(281 and 283) for corrected rear wheel HP. Sorry.
Graph: https://www.ford-trucks.com/forums/1444437-robs-project-tan-truck-8.html#post18840312
It's really weird feeling with that setup - she's kind of cold blooded; she fires right up with glow plugs though... but smokes and just sounds retarded down low. I've corrected as much as I can, but it's one of those things where it really loses power up top if you advance it too much; kind of felt like when I had the decompression gaskets on a previous build with stock cam.
I'm still holding out hope that a (properly ground) torque cam can be better than stock, as it should keep that low end compresson... but my stage 1 cam just isn't for me.
carsonlhammond
Full Access Member
Sounds to me like you’re feeling the effects of low air velocity at low rpms caused by the overlap of valve timing in a high lift/duration cam designed for high rpm power. (Which I believe is what Justin’s cam is designed for) Personally I think my truck has lost a little on the top end but definitely feels like a different beast down low compared to other manual 6.9’s I’ve driven. (I have Typ4’s low end cam in my highboy)
Looking at the graph almost looks like you’re loosing fuel pressure and compensating with base timing, you should be seeing more power than that.
I did notice you said no ones made more than 200 with a stock pump and turbo kit, I’ve made over double that with a stock pump and stock 088 kit. My customer was testing a db2 fueling kit that I’m putting together that will allow people to do some basic upgrades to their stock pumps and get some good performance on a budget.
This kit replaces the governor spring, the delivery valve, delivery valve spring and stop, the metering valve, the guide stud nut, the advance piston, and the advance piston bore caps. Then following the instructions the pump is retuned for maximum output.
We were not expecting anywhere near the kind of numbers we got, the first run was the truck as it came in off the road bone stock with just the turbo kit. The next was just the fueling mods, which added almost a hundred horsepower. Then he sprayed it with some nitrous after adding another 30 psi of transfer pressure, and picked up over another hundred horsepower, and almost hit 800ft lbs.
I did notice you said no ones made more than 200 with a stock pump and turbo kit, I’ve made over double that with a stock pump and stock 088 kit. My customer was testing a db2 fueling kit that I’m putting together that will allow people to do some basic upgrades to their stock pumps and get some good performance on a budget.
This kit replaces the governor spring, the delivery valve, delivery valve spring and stop, the metering valve, the guide stud nut, the advance piston, and the advance piston bore caps. Then following the instructions the pump is retuned for maximum output.
We were not expecting anywhere near the kind of numbers we got, the first run was the truck as it came in off the road bone stock with just the turbo kit. The next was just the fueling mods, which added almost a hundred horsepower. Then he sprayed it with some nitrous after adding another 30 psi of transfer pressure, and picked up over another hundred horsepower, and almost hit 800ft lbs.
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Those numbers didnt make any sense! Until I saw the blurb about nitrous. What was the smoke situation like? Impressive in any case.
Any guess about pump longevity with that kit installed?
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With the nitrous no smoke at all, but fuel only it was pretty bad with how long the 088 takes to spool. Pump should actually last longer with all the new parts and wear components replaced like the advance piston, delivery valve and metering valve.
The limitation that will eventually kill the pump is transfer pressure will keep dropping from advance piston bore wear and it will make less and less fuel until it won’t hot start well.
Would definitely be interested when you get passed testing phase.
I saw an IDI with an hx35/40 hybrid. Spooled very quick off idle. Faster than what most idi guys are using.
You have a favorite setup you'd use in a situation like that? Fast spooling with efficient 300+ hp potential?
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