Need some ideas on what happened

[Newold1]

That's kinda what I thought. Watched these type of jet boats run up on the Snake river. Some wild crazy hard on boat, engine and driver river racing!

Looks like some serious dollars in that impeller housing?

[jet1]

Well I build them so a bunch cheaper for me.lol. I made pretty much all of the ones in any of the turbines running on the Snake.

[jet1]

Really hard to add separate bungs for egt’s because of the water jacketing.

[In-Tech]

It's a pain. Drill through both layers, then take a small ball peen hammer and peen the outer layer into the inner layer and tig to seal the layers in that spot. Pressure test if you don't trust your weld, then weld a bung to what you just welded. It's important to try to get the distance to the flange as close as you can on all ports since EGT probes don't react very quick, also the depth of each probe is critical too. It's the same thing we do on double wall collectors when we install a wide band and can be done in each port the same way. Sometimes that can be hard depending on the room you have(packaging) since the wide bands are so large.

edit, wide bands are kinda a no-no on the pressure side(looks like you have a turbo) but do-able for testing and when done, move to outlet of turbo once you have finished your individual cylinder tuning.

[MadBill]

..edit, wide bands are kinda a no-no on the pressure side(looks like you have a turbo) but do-able for testing and when done, move to outlet of turbo once you have finished your individual cylinder tuning.

Not sure about this, but I'd heard that the problem with high pressure on O2 sensors was a drift in the indicated AFR. If that's all, readings could probably be corrected.

[In-Tech]

Yes Bill, agreed...pressure and heat. David R can probably answer better than I.

What our plan is so far is to repair the engine and install egts in each cylinder ex pipe(hard to do with water cooled headers) we are going to check the reluctor wheel to make sure that it in the proper place and then verify as soon as we start it with a light. change to a typical mechanical water pump.

Hiya, all good ideas. Do you have the jig to check the reluctor wheel? I generally key my cranks/balancers for future use with a supercharger and then make a pointer to verify the timing is what I am commanding.

A note on the EGT, you probably know but try your best to keep the bung the same distance from the flange as well as make sure the depth of the probe is the same between cylinders(very important). The open end probes react the fastest and are best for dyno testing, the inconel sheath will last longer but is obviously slower to react. I have seen marine stuff handle continuous use at ~1650F egt although I don't like it. My turbo stuff would usually stabilize around 1450f when I am finished(many variables to accomplish).

By stabilize I mean the EGT has started to hover and dance a few degrees either way under full power conditions, definitely monitor it at light throttle too, even though the mass flow is lower. At under 100 kpa situations the intake will bounce more. Truly you want to use 8 egt and 8 wideband. What that can show(after tuning) is equalization of the AFR and see major changes in egt between cylinders. Now you are seeing different mass flow between cylinders meaning more work = more egt. Of course this happens no matter the kpa but more pronounced usually at lower kpa.

How do you control the heat, by altering timing and enrichment?

Sorry I missed your question, yes you do the above but most critical is valve timing.

I don't care(in general) that this is a small cubic inch engine, it's still about mass flow and time. That cam is too small, the heat has to be ridden of. Time/rpm dictates it would benefit from a good mechanical roller around 260@.050" single pattern on a very similar LSA as what you are running.

[Turborick]

Ok so now I am looking at the valve springs. They are a pac 1243 240 closed and 560 over the nose. The spring itself is 140 grams with steel retainer and stainless valve. I am not really a fan of the springs and I really cannot tell you why. I like either the comp cams dual conical or the psi 1575 ml.
Just so you don’t have to read the whole post the application is.
260 ci ls based engine
Twin 60 mm turbos
8.7:1 comp
Mast 225 cc small bore heads
Solid roller 244/248 115lc .662/.662 at the valve.
Extreme endurance, 30 min wot at 6800-7400.

I run a turbo 259 inch small block Chevy in a land speed application where our runs take approximately 90 seconds.
I run the 1343 PAC on the intakes and 1344 PAC on the exhaust we turn the motor 10,000 RPM. And have had pretty good life with the springs

Very interesting. the springs I have decided on are very close to what you are running on the exhaust but are way lighter at 111 gr vs 143. Are you running ti intake valves? I am running Stainless as i have had issues trying to run Ti before.

Yes we run ti on the intakes and they live better than the Inconel exhaust valves. What spring have you decided to run?

[rustbucket79]

Does the added duration (and presumably overlap) create some passive exhaust contamination in the combustion chamber which would lower the combustion temperature? Or is it about blowing some of the intake charge out the exhaust, cooling the exhaust valve and port?

[Kevin Johnson]

When I figure out how it is related to hull impact vibrations I will report in.

[ptuomov]

Bad ass manifolds.

Any way to get a sensor in thru the flange?

[jet1]

I run a turbo 259 inch small block Chevy in a land speed application where our runs take approximately 90 seconds.
I run the 1343 PAC on the intakes and 1344 PAC on the exhaust we turn the motor 10,000 RPM. And have had pretty good life with the springs

Very interesting. the springs I have decided on are very close to what you are running on the exhaust but are way lighter at 111 gr vs 143. Are you running ti intake valves? I am running Stainless as i have had issues trying to run Ti before.

Yes we run ti on the intakes and they live better than the Inconel exhaust valves. What spring have you decided to run?

I am going to use a JHE spring made by PSI called an x650. 190 on the seat with a 674 rate.

[jet1]

Yes Bill, agreed...pressure and heat. David R can probably answer better than I.

Hiya, all good ideas. Do you have the jig to check the reluctor wheel? I generally key my cranks/balancers for future use with a supercharger and then make a pointer to verify the timing is what I am commanding.

A note on the EGT, you probably know but try your best to keep the bung the same distance from the flange as well as make sure the depth of the probe is the same between cylinders(very important). The open end probes react the fastest and are best for dyno testing, the inconel sheath will last longer but is obviously slower to react. I have seen marine stuff handle continuous use at ~1650F egt although I don't like it. My turbo stuff would usually stabilize around 1450f when I am finished(many variables to accomplish).

By stabilize I mean the EGT has started to hover and dance a few degrees either way under full power conditions, definitely monitor it at light throttle too, even though the mass flow is lower. At under 100 kpa situations the intake will bounce more. Truly you want to use 8 egt and 8 wideband. What that can show(after tuning) is equalization of the AFR and see major changes in egt between cylinders. Now you are seeing different mass flow between cylinders meaning more work = more egt. Of course this happens no matter the kpa but more pronounced usually at lower kpa.

How do you control the heat, by altering timing and enrichment?

Sorry I missed your question, yes you do the above but most critical is valve timing.

I don't care(in general) that this is a small cubic inch engine, it's still about mass flow and time. That cam is too small, the heat has to be ridden of. Time/rpm dictates it would benefit from a good mechanical roller around 260@.050" single pattern on a very similar LSA as what you are running.

Ok now that is confusing, with the cam we have now it hasn't even hit peak tq by 7300 rpm. I can see the 260 dur cam taking the heat out because it won't be making any power around 7000 is all.
I am pretty much out of room with putting egt's in each pipe. oil lines run on that side and a water manifold for the header not shown in the picture is on that side.

[In-Tech]

Ok now that is confusing, with the cam we have now it hasn't even hit peak tq by 7300 rpm. I can see the 260 dur cam taking the heat out because it won't be making any power around 7000 is all.
I am pretty much out of room with putting egt's in each pipe. oil lines run on that side and a water manifold for the header not shown in the picture is on that side.

Did you mean peak TQ or peak HP at 7300? If boost is constant I have a hard time with it not making peak torque by 7300rpm.

Unlike a wide band, the EGT probe's can be on the underside of the header.

[jet1]

Ok now that is confusing, with the cam we have now it hasn't even hit peak tq by 7300 rpm. I can see the 260 dur cam taking the heat out because it won't be making any power around 7000 is all.
I am pretty much out of room with putting egt's in each pipe. oil lines run on that side and a water manifold for the header not shown in the picture is on that side.

Did you mean peak TQ or peak HP at 7300? If boost is constant I have a hard time with it not making peak torque by 7300rpm.

Unlike a wide band, the EGT probe's can be on the underside of the header.

In this one we only went to 7200 and tq was still increasing at 11 psi consistent. The bottom of the header is where the water enters the header from the manifold. Sorry don't have a picture for that one.

IMG_3738.JPG

[ptuomov]

Wouldn't that say that the exhaust cam is more likely to be too long duration than too short duration?