High EGT,s on HX55 WM, 4x560 diesel endurance raceboat

7

7075T6

New member
Need some advice..

I´ve got the FPT 6,7-560 engines in my raceboat.
Very similar to the Cummins 6,7 but slightly different bore/stroke and 3150 rpm ceiling vs 3300 on the Cummins.
Also low c/r at 14,1:1.

Need another 50-60 hp/engine to get the boat running the way I want.
That shouldn´t be a problem. But.. Also need more power at low revs to get the boat on plane easier.

That is the issue when you need to go from zero to 100 mph in one gear and have 3150 rpm to play with..

Cool seawater and large heatexchangers/oilcoolers keep the water and oiltemps at ok levels.

The problem is the EGT-numbers. After only a minute at WOT the EGT,s reach 1350-1400 F.
Then I need to go below 2800 rpm for a while to cool things down.

Depending on seastate the engines are under full load for long periods as enduranceraces can last several hours.

Turbos are Holset HX55WM, gated, 41 psi boost.
Watercooled turbinehousings and T3 waterjacket flanges.

Can´t find any data but measured them:

Comp 100 mm exd, 70 ind
Turb 96 ind, 71 exd

Don´t know the size of turbinehousing. 14? Se pic.

Any ideas out there?
 

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i'm not familiar with your engine or how boats work. however excessive heat at WOT relates to two things. too much fuel at WOT or not enough turbo.

can you back off some fueling above 3000rpms? just enough to pull the heat out of it? that would be the cheapest fix. a little tuning with the ol laptop goes a long way.

what is your drive pressure? if your housings are to small you could be choking up the exhaust to much and building heat instead of power. again by loosing a bit of potential over fueling up top DP would go down. if you are seeing high drive pressures this might help. just because you take a bit of fuel away doesn't always mean you loose HP.

If drive pressures are too high which means your housings are probably to small for those rpms, would it be possible to install external wastegates somewhere in the exhaust, or modify your current housings to flow better? this would allow the engine to breath from a bigger straw and free up some ponies and loose some heat/drive pressure.
 
turbo2387 said:
i'm not familiar with your engine or how boats work. however excessive heat at WOT relates to two things. too much fuel at WOT or not enough turbo.

can you back off some fueling above 3000rpms? just enough to pull the heat out of it? that would be the cheapest fix. a little tuning with the ol laptop goes a long way.

what is your drive pressure? if your housings are to small you could be choking up the exhaust to much and building heat instead of power. again by loosing a bit of potential over fueling up top DP would go down. if you are seeing high drive pressures this might help. just because you take a bit of fuel away doesn't always mean you loose HP.

If drive pressures are too high which means your housings are probably to small for those rpms, would it be possible to install external wastegates somewhere in the exhaust, or modify your current housings to flow better? this would allow the engine to breath from a bigger straw and free up some ponies and loose some heat/drive pressure.
Click to expand...

Don´t have the drivepressure readings. Will make fittings for sender during winter. Bit tricky with the watercooled housings.
 
We did a pair of turbochargers for a twin 3406E engine race boat on lake michigan. His requirements were 1000hp per engine and lightning fast response. You boat guys sure make it tough on us turbo guys LOL Luckily SIS (cats parts program) made it a little easier on us as they at least give SOME info on the turbochargers.


Can you measure the turbine wheel? There are quite a few flavors of turbine for the HX55 turbochargers. A simple turbine upgrade can do wonders.
 
zfaylor said:
We did a pair of turbochargers for a twin 3406E engine race boat on lake michigan. His requirements were 1000hp per engine and lightning fast response. You boat guys sure make it tough on us turbo guys LOL Luckily SIS (cats parts program) made it a little easier on us as they at least give SOME info on the turbochargers.


Can you measure the turbine wheel? There are quite a few flavors of turbine for the HX55 turbochargers. A simple turbine upgrade can do wonders.
Click to expand...

Ok. Here.
 

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Is there any adjustment on your wastegate? Ideally I would look into a twin turbo setup. Faster spool up with greater top end flow.

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
badbowtie said:
Is there any adjustment on your wastegate? Ideally I would look into a twin turbo setup. Faster spool up with greater top end flow.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Click to expand...

Adjustment,yes.

Twin turbo. No..LOT of work and money with 4 engines..:aiwebs_027:
 
I get budgets, but it really is the best of both worlds. I would try to tighten down your wastegates just to see if more air would cool your egts , or if it will just be too hot to help. The only downside is even if it helps on top it won't affect the bottom end at all.

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
you should test each wastegate with compressed air and see when the gates are actually opening.

are they functioning
are they staying closed too long
are they opening too soon
are the diaphragm's leaking?

also. how much HP are these engines making?
 
Last edited:
turbo2387 said:
you should test each wastegate with compressed air and see when the gates are actually opening.

are they functioning
are they staying closed too long
are they opening too soon
are the diaphragm's leaking?

also. how much HP are these engines making?
Click to expand...
Will check gates. Diaphragms should be ok. Only 30 hours on the engines.
560 hp at 3000 rpm.

Skickat från min F5321 via Tapatalk
 
70/71/??? is gonna be close at sustained HP controlling temps.

to temps creep up or shoot straight to 1400*
 
OP looks like you have the 86x77 turbine. As mentioned there is an 86x80 available as well. As long as the turbine housing isn't an issue we could easily upgrade those on both ends if desired.
 
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