six shooter
Quiet Member
- Joined
- May 26, 2001
Do you think this new combo would be happier with more mechanical compression ratio ?
Advancement of fuel delivery?
- Thread starter Alky V6
- Start date
Yeah. It would certainly help off boost and to spool the turbo. But, the low CR does a good job of keeping me out of trouble.
After some testing tonight I'm pretty sure you will need a sizeable amount of "exhaust energy" (n2o) to maintain the targeted boost level, unless my tune is WAY off or alcohol makes that much more power. :redface: I hope you have better success than me Don! 
( i'm sure you will)
scott wile
( i'm sure you will)scott wile
I've already determined from the last time out with the car that once the car is on boost it can maintain it without the nitrous. At least, that goes for the last tested target boost of 260 kPa (24 psi). In fact, the boost rose very sharply in first gear to well over target boost to just over 300 kPa without any sign of nosing over before the controls brought it back sharply to target level. It was nice to not see any dropping of the boost level during the duration of the run for once. There was a short spike on the 2-3 shift. If the testing tonight shows that the mixture has room, I'll be stepping up the boost target. 2 psi steps. Watching the fueling level. I still have the wall and the upper right region of the fuel map to dial in. The fuel pump booster is at 42% now. If it looks like I'm running out of fueling after the booster is maxed to 50%, it'll be time to figure out a new injector nozzle size for the aux fueling. I'm confident the existing nozzles will take me to at least 32 psi.After some testing tonight I'm pretty sure you will need a sizeable amount of "exhaust energy" (n2o) to maintain the targeted boost level, unless my tune is WAY off or alcohol makes that much more power. :redface: I hope you have better success than me Don!
scott wile
The ultimate target is 40 to 45 psi. That's where the low static CR I'm running is helping me out. At that boost level the fuel will be getting the heat it needs. Of course, I don't think I'll be seeing that boost level with these tires though.
That goes to show you how much more 'product of combustion' (exhaust volume) there is with the methanol compared to gasoline. I'm able to maintain that boost with this small engine and large turbo, and with an exhaust temp of only 1100 to 1200 F.
six shooter
Quiet Member
- Joined
- May 26, 2001
Details for the curious ??Correct, Scott.
Launching on concrete netted a certain amount of tire spin which let the engine rpm rise throughout the launch at a different rate than it does on a prepped launch pad. With the tires sticking much better on the prepped track, the engine rpm took more time to rise relative to car speed and the nitrous tune was too lean for that situation. Some ground electrodes were happy to tell me so. The nitrous was tuned on the lean side for the concrete launch and was too lean for the prepped track launch. I'll be lowering the nitrous tune a few jet sizes and work up from there.
The fueling system needs some upgrading. With the engine breathing better, and the boost coming in so late, this engine wants more fuel than the present setup can deliver. A major obstacle is the wall. With all the fueling bumped up, I've run out of room (duty cycle) to move the wall higher. At the very least I need to do something to lower the level of the wall or eliminate it. On the upper end, it looks like I'm going to need larger nozzles or switch to electronic injectors or a rising volume mechanical injection pump for the nozzles. The better breathing has turned this engine into a fuel hungry monster. Though I'm not quite to 50% voltage boost on the fuel pump, I can see that the fueling is going to be too much on the limit for me to increase boost in the future.
Other measures to get this turbo spooled will need to be taken. A switch to a 1.0 a/r turbine housing and a higher stalling T/C will be first on the list. Maybe a torque converter feed strategy is in the future.
Launching on concrete netted a certain amount of tire spin which let the engine rpm rise throughout the launch at a different rate than it does on a prepped launch pad. With the tires sticking much better on the prepped track, the engine rpm took more time to rise relative to car speed and the nitrous tune was too lean for that situation. Some ground electrodes were happy to tell me so. The nitrous was tuned on the lean side for the concrete launch and was too lean for the prepped track launch. I'll be lowering the nitrous tune a few jet sizes and work up from there.
The fueling system needs some upgrading. With the engine breathing better, and the boost coming in so late, this engine wants more fuel than the present setup can deliver. A major obstacle is the wall. With all the fueling bumped up, I've run out of room (duty cycle) to move the wall higher. At the very least I need to do something to lower the level of the wall or eliminate it. On the upper end, it looks like I'm going to need larger nozzles or switch to electronic injectors or a rising volume mechanical injection pump for the nozzles. The better breathing has turned this engine into a fuel hungry monster. Though I'm not quite to 50% voltage boost on the fuel pump, I can see that the fueling is going to be too much on the limit for me to increase boost in the future.
Other measures to get this turbo spooled will need to be taken. A switch to a 1.0 a/r turbine housing and a higher stalling T/C will be first on the list. Maybe a torque converter feed strategy is in the future.
On one of the last runs, the engine gave me a glimpse of what it's capable of. The tuneup being way off, the engine took until third gear to spool. When it did, the car was fish tailing, hitting the rev limiter, doing a burnout across the finish line as if I was in the freaking water box! 30 psi with this turbo is definitely different than the 30 psi with the T76. I'll definitely be needing some chassis upgrading before I move above 30 psi with this turbo.
Not really sure what the boost was on that run. The datalog messed up on me. The boost controller was set at 24, but past datalogs showed a tendancy for the boost to have a sharp spike to around 29 to 30 before quickly settling in at 24. Regardless, the performance was very impressive. Reports from fellows at the starting line, watching the run were that they could hear the tires screeching when the turbo came up while crossing the finish line.
Not really sure what the boost was on that run. The datalog messed up on me. The boost controller was set at 24, but past datalogs showed a tendancy for the boost to have a sharp spike to around 29 to 30 before quickly settling in at 24. Regardless, the performance was very impressive. Reports from fellows at the starting line, watching the run were that they could hear the tires screeching when the turbo came up while crossing the finish line.
If the switch from the present 1.15 a/r turbine housing to a 1.0 a/r allows 135 kPa by 5400 to 5600 rpm, that would be very nice. That would be a drop of about 600 to 900 rpm from the present level. According to JZ, the a/r change could net a change in the rpm-to-map rise by as much as 1,000 to 1,500 rpm. A change of 1,000 would put 135 kPa at 5,300 rpm. A change of 1,500 would put 135 kPa at 4,800 rpm. Still, that amount of drop in rpm-to-map would work out nicely.
The change from 1.15 to 1.0 a/r will naturally choke the engine down on the top end, but in my circumstance, I don't think I'll notice it. In my case, I think I could benefit a little if the 1.0 tamed the engine down a little on the top end. Especially, with my present chassis arrangement.
Does anyone have any experience changing out a turbine housing a/r at this level? And what kind of change did you get in rpm-to-map rise? Are my expectations too optimistic?
The change from 1.15 to 1.0 a/r will naturally choke the engine down on the top end, but in my circumstance, I don't think I'll notice it. In my case, I think I could benefit a little if the 1.0 tamed the engine down a little on the top end. Especially, with my present chassis arrangement.
Does anyone have any experience changing out a turbine housing a/r at this level? And what kind of change did you get in rpm-to-map rise? Are my expectations too optimistic?
six shooter
Quiet Member
- Joined
- May 26, 2001
For what it's worth , I think this quote applies here - "Perseverance is the key to innovation's endless possibilities and varieties locked within each of us."
You will work it out and then
The engine is down for a PMing. The last time out stressed the head gaskets too much.
Everything in the engine looks absolutely beautiful. Bearing wear was even and minor. This is with an aluminum block, mind you. I'm tempted to even reuse the bearings. I won't though.
The Felpro wirelocks though, were beat to heck. The fire rings separated from the rest of the gasket and were floating in the groove. I'm going top fuel baby! I'm switching to SCE copper gaskets with stainless steel o-rings in the heads and receiver grooves in the top of the sleeves. A coating of hylomar to seal the water and oil passages. An initial warmup with no cooling system pressure, and a retorque procedure will be followed. This should allow the higher boost settings when I'm ready.
The geardrive idler bearing was a surprise. I was expecting a little wobble out of the ball bearing at this point, but it's tight and there is no sign of the slightest wobble. As if it was brand new. Cool. The rest of the valvetrain is wearing fantastically too. New valve springs, of course.
Flexplate stayed tight to the crankshaft. The higher torque value with the ARP bolts helped there.
A 1.0 a/r housing and a stator change in the torque converter will be installed for the next tuning sessions.
The Total Seal gapless top, metric size, low tension rings seemed to control the 25-50 oil well. Chamber residue was minimum and ring lands clean.
Redline water wetter controlled corrosion levels very well.
Everything in the engine looks absolutely beautiful. Bearing wear was even and minor. This is with an aluminum block, mind you. I'm tempted to even reuse the bearings. I won't though.
The Felpro wirelocks though, were beat to heck. The fire rings separated from the rest of the gasket and were floating in the groove. I'm going top fuel baby!
I'm switching to SCE copper gaskets with stainless steel o-rings in the heads and receiver grooves in the top of the sleeves. A coating of hylomar to seal the water and oil passages. An initial warmup with no cooling system pressure, and a retorque procedure will be followed. This should allow the higher boost settings when I'm ready.The geardrive idler bearing was a surprise. I was expecting a little wobble out of the ball bearing at this point, but it's tight and there is no sign of the slightest wobble. As if it was brand new. Cool. The rest of the valvetrain is wearing fantastically too. New valve springs, of course.
Flexplate stayed tight to the crankshaft. The higher torque value with the ARP bolts helped there.
A 1.0 a/r housing and a stator change in the torque converter will be installed for the next tuning sessions.
The Total Seal gapless top, metric size, low tension rings seemed to control the 25-50 oil well. Chamber residue was minimum and ring lands clean.
Redline water wetter controlled corrosion levels very well.
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
In the cool air I can run a 1.32 a/r on my 94mm but when the summer heat got here I could not get enough launch boost. I was at 4# in the cool air and 1.5# in the heat. Swapping to the 1.0 from the 1.32 gained 4# of launch boost at the same rpm and full boost comes on .5 second quicker.
Rusty, At what rpm would you reach 8 psi boost with the 1.32 housing and then at what rpm would you reach 8 psi boost level with the 1.0?
I did some quick fuel calculations and it looks like I'm going to need about 185 to 190 lbs/hr from my mechanical injection nozzles if I'm to ever reach my ultimate goal with these heads. Total fuel flow of 320 to 340 lbs/hr. I'm seriously considering mounting a mechanical fuel pump to supply the fuel nozzles. It would be a separate system running next to the electronic system that would carry a higher line pressure than the electronic system. I was hoping I wouldn't have to do this, but it looks like if I were to stick with all electronic injectors, I would need three injectors per runner (160 pounders). I remember someone mentioning that there are larger electronic injectors now, but are they restricted by working pressure? I can run higher pressure with the mechanical system and get better atomization? I already have some ideas on how to run a bypass and check valve to control when the mechanical nozzles would come in. The new stradegy would eliminate the fueling wall that I'm fighting with. The mechanical pump would allow a gradual increase in fuel volume from the mechanical nozzles rather than the steady rate throughout the rpm and map rise that I was working with before. The more I think about it, the more flexible this new system is starting to sound. Just may be the ticket. Electronic injector cut back would not have to be as profound too.
Scott, you did it again. Massive Ooooh!!!
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