Forced Induction's FI91X report!

[lazaris]

Otto, yes the 88, would eliminate the need for nitrous, but lets look at how many buicks are honestly running mid to low 8's with an 88. We have seen a few, but most are back halved cars, running much bigger tires and lets be honest, pushing way more then 26-30#'s boost, more like 37-42#'s, which means lots of rebuild cost. Fiscus is the only guy right now that I know with a stock styl susp, running faster then 8.50's most of the time. The Reason a few of us crazy guys run something different and bigger, is to NOT have to push our cars that Hard to hit a number. Should we ever want to go faster, then we have the heads and the turbo already to go for a later build. :smile:

Not so sure about that. I believe Ted A is running those times with out maxing his out yet. As far as a bigger turbo and not pushing it, I believe in the end whether its a larger turbo running 25 psi or smaller turbo running 30 psi to run the same ET and MPH its all very similar. As long as intake temps are reasonable the cylinder presure to run those times should be similar from either turbo.

 

[Dusty Bradford]

Not so sure about that. I believe Ted A is running those times with out maxing his out yet. As far as a bigger turbo and not pushing it, I believe in the end whether its a larger turbo running 25 psi or smaller turbo running 30 psi to run the same ET and MPH its all very similar. As long as intake temps are reasonable the cylinder presure to run those times should be similar from either turbo.

The big difference in the 88 like Fiscus is using and the larger turbo's like Quint and Don are using is the large turbine wheel. Quint's is a turbo large enough to support a 360ci V8 so it has very low backpressure. You use the n2o to spool and then the motor will make more power at less boost due to the reduction in backpressure.

 

[Alky V6]

The way I look at it, if there is any reasonable way to spool a particular turbo, and you can stay away from compressor surge, then you should use a turbo that will give you the most efficient compressor side range for your application. With that turbo you would be able to obtain a target hp level using less boost due to a cooler and more dense charge straight out of the compressor, and because of that there is less thermal and pressure loading on the intake system, cooler combustion temps and a larger fuel detonation buffer zone. Less thermal loading of the engine overall, allowing more runs between teardowns.

If you were at a top fuel meet and told the crew chiefs that there was a tent down the way displaying a blower that was just one percent more efficient than anything they've ever seen, you can bet those people would be tripping all over themselves to get to that tent to see what's up.

 

[Alky V6]

The big difference in the 88 like Fiscus is using and the larger turbo's like Quint and Don are using is the large turbine wheel. Quint's is a turbo large enough to support a 360ci V8 so it has very low backpressure. You use the n2o to spool and then the motor will make more power at less boost due to the reduction in backpressure.

The turbine housing on the FI91X, I've found out, is a BW S510 unit. I'm sure it's capability is up there too. What's nice about using a low back pressure turbine arrangement, it opens up a wide range of camshaft options. You can start taking full advantage of crossover, increasing VE.

 

[S2V6RACER]

Otto, yes the 88, would eliminate the need for nitrous, but lets look at how many buicks are honestly running mid to low 8's with an 88. We have seen a few, but most are back halved cars, running much bigger tires and lets be honest, pushing way more then 26-30#'s boost, more like 37-42#'s, which means lots of rebuild cost. Fiscus is the only guy right now that I know with a stock styl susp, running faster then 8.50's most of the time. The Reason a few of us crazy guys run something different and bigger, is to NOT have to push our cars that Hard to hit a number. Should we ever want to go faster, then we have the heads and the turbo already to go for a later build. :smile:

I have ran consistent 8.5x at 28psi with low timing and a little rich A/F ramping boost in real slow. I have ran my best MPH (164.6) at 30.01 PSI (at 2.4 seconds after the leave) not leaning on the timing or A/F yet, oh with the little T4 88 turbo. I have over 60 passes on my combo. No NOS, and can be on boost in .08 seconds when the gas hits the floor on the second bulb (No NOS either). I am not leaning on the engine to get these times, we just have a good combo and the TA heads have served us real well.

 

[John Wilde]

I have ran consistent 8.5x at 28psi with low timing and a little rich A/F ramping boost in real slow. I have ran my best MPH (164.6) at 30.01 PSI (at 2.4 seconds after the leave) not leaning on the timing or A/F yet, oh with the little T4 88 turbo. I have over 60 passes on my combo. No NOS, and can be on boost in .08 seconds when the gas hits the floor on the second bulb (No NOS either). I am not leaning on the engine to get these times, we just have a good combo and the TA heads have served us real well.

Damn that is fast for what you have!!!
Sick car dude!!!

 

[Quint]

I have ran consistent 8.5x at 28psi with low timing and a little rich A/F ramping boost in real slow. I have ran my best MPH (164.6) at 30.01 PSI (at 2.4 seconds after the leave) not leaning on the timing or A/F yet, oh with the little T4 88 turbo. I have over 60 passes on my combo. No NOS, and can be on boost in .08 seconds when the gas hits the floor on the second bulb (No NOS either). I am not leaning on the engine to get these times, we just have a good combo and the TA heads have served us real well.

No doubt about it Ted, your car is working very well. Again, not allot of cars like yours and Fiscus running that well with similar setups. You guys are the benchmarks that i have wanted "fear" to duplicate and then some . Running Mid 8's and faster with stock type susp on these types of tires, is just not as easy as most may think you know. The boost ramp with out NOS is impressive and I have often thought why not go with a 88,and leave the NOS at home.

 

[Otto J]

Not sure about your car Quint,But Teds car also weighs 3400+ and does those time,It is a really well thought out program Ted has.
I know Don said his weighs low 3200 i believe.
Its my opinion that the 91 may get you where he is but if everything is not right you will be running all of 30#s+ to get there and still need NOS to get it spooled.
The new PTC convertor they did for Gallinas car is spooling twin 42-76s and they no longer need the NOS to get it spooled.

 

[Alky V6]

Well, I never expected to be able to get a turbo to spool quickly with my combo. Heck. I've pretty much done every single thing possible to make quick spooling impossible.

 

[Quint]

Not sure about your car Quint,But Teds car also weighs 3400+ and does those time,It is a really well thought out program Ted has.
I know Don said his weighs low 3200 i believe.
Its my opinion that the 91 may get you where he is but if everything is not right you will be running all of 30#s+ to get there and still need NOS to get it spooled.
The new PTC convertor they did for Gallinas car is spooling twin 42-76s and they no longer need the NOS to get it spooled.

True Otto, very true. I wish my car was lighter, im still on the heavier side, since it still an all steel car with non of the light weight stuff yet. I know this for sure, and I have always said this, though the 88 and 91 or 91.5 like are similar, one thing is different and thats the way the car moves out. I know of a couple of friends that used the smaller 88's and those things came into boost "real" fast like Ted was saying. Easily grabing bumpers. The way my car moves out isnt quite as cool looking as those. It leaves ok, but once you grab 2nd and start going, thats when it really starts to wake up. It doesnt seem to be the "wild" ride that most guys would have hitting 8's. Its very Ho hum, in my opinion. I could put a novice in the car and set it low on the launch RPM and so long as they hit the shifts, it will do an 8, but with no drama. The 8.83 I ran, just didnt feel like an 8 sec pass, especially since I messed up the 2-3 shift and was only pulling 24.8 #'s in the end. I guess everyone's set up is a little different and thats what makes them unique in its own right. The coolest thing about these buicks, is the ones who can go 8's with ease, is just plain mind boggling. You have guys at the track with 2 more cyl, and your laying the smack down and they are sitting back just wondering what the heck happened. You gotta love the Dark Side

 

[Alky V6]

I don't see myself ever giving up the nitrous. Even though I've done everything in the book to make spooling as hard as possible, I've also done everything in the book to make my setup as efficient as possible when on the turbo. Tuning in a simple nitrous system, simply changing some jets, seems to me to be a very simple thing compared to trying different turbos, changing out torque converters, and coming up with special spooling tuneups, some of which can damage parts, or any other 'top secret' parts or procedures. In my opinion, anything that I would do to make spool up quicker, completely without the use of nitrous, would have to be a major compromise for my particular configuration.

I'll post up my lastest datalog when I get the chance.

 

[Alky V6]

I'm going to post a series of frames from my latest test run. This is the run that netted a 6.7x @ 113.xx. This was with a 245 level nitrous shot.
The detail line will move along the timeline to highlight different key points during the run.

This first frame was in the staging lights at the point just before the nitrous hit.

Throttle is at 4.14v. This is full throttle.
MAP is at 92.9kPa. 98kPa is 0 vacuum, 0 boost with my system.

 

[Alky V6]

This frame is at the point just before the transbrake is released. The nitrous has been previously energized. You can see the quick rise in rpm at the point of the nitrous hit and then the rpm starts to level off as it stalls the torque converter at 3548 rpm. MAP is now 94.2kPa.

 

[Alky V6]

This frame is of great interest. This is the point that the nitrous has just shut off, the wall is about to hit, and the boost climb greatly steepens. The time stamps are accurate so that the time from transbrake release to 8-9 psi can be calculated.

RPM 5807
MAP 153.5kPa. I'd be real happy if this boost level was happening at 5400 rpm. If I remember right, with the 190 shot, I was reaching this boost level by 6500+ rpm. That was also with the open turbine housing.
MAT is steady at 26C. The liquid intercooler is doing a good job of heatsinking the initial temperature rise of intake air at the start of the run.
As you will see in the next frame, there is a slight increase in rpm as the nitrous comes off and the fueling table hits 'the wall'. The detail line is covering it right now.

 

[Alky V6]

At this frame the rpm is at the top of first gear. The shift to second has just been made. The MAP is just above the boost controller set level (254kPa).
The spring package in the wastegate is one level too firm. That can be seen by how far the boost spikes before the wastegate is able to bring the boost back.
MAT just starts to rise.

Right after this detail line you can see where the rpm just slightly starts to drop due to the shift to second, then the tires break loose. In the MAP and TPS views you can see that I was busy trying to gain back traction. Look at how far I came off the throttle a few times. Even after coming off the throttle that much, the turbo was able to come right back with boost when I opened her back up. The boost followed the throttle very well. Some would have thought that with having to get off the throttle that much with the large turbo, I would have lost the spool up, ruining the chance of the boost being able to recover in a reasonable time. That is not the case with this setup.

 

[Alky V6]

In this frame, the detail line is at the end of 2nd gear. You can see that just before the shift, the rpm settled down due to the tires gaining some traction. I was still off the throttle a little and I decided to try to keep the traction by short shifting to 3rd gear. After shifting to 3rd, I went WOT for the rest of the run. Note the MAP. Another spike as I went back to WOT.
At the 2-3 shift, rpm dropped from 6474 to 5562 while throttling.

 

[Alky V6]

This frame is where I went back to WOT. Notice the rpm rose a bit from the increased boost at this point. MAP spiked just as I came back to WOT. The turbo obviously being very responsive to the throttle position.

Also note the rpm at this point. This little engine has absolutely no problem getting the spool back up on this monster turbo in this rpm range. Very impressive.

 

[ttypewhite]

Don't forget Avon, he also has a mid 8 sec car that runs like a bat outta hell. Billy has him well dialed in also.
Keep pushin Don, you gotta like a guy that thinks outside the box.

 

[Alky V6]

This is the last frame before coming off the throttle at the end of the run.
IAT at 46C. A rise of 20C throughout the run.

So I wonder what percentage of the total run was I off the throttle? I just went back and checked. 1.2 seconds.

Some small notes that will be important to track as I work up the nitrous tune;
The time from transbrake release to an important target of 136.7kPa: 1.56 seconds. The 60 foot on this run was 1.66.
The rpm at 136.7kPa: 5376.

 

[Alky V6]

If anyone would like to see the detail line at any other point besides the ones I've already posted, let me know and I'll get it posted for you.