968 Supercharger Kit Development
06-02-2009, 11:06 AM
#211
Instructor
savass944....
as was stated earlier in the thread, Carl is looking to minimize cost and complexity in the kit design; both of which would be negatively affected by the addition of an inter-cooler.
I live in Las Vegas, where our average daily temps are ~ 82F, with summers running in the 100F+ range for at least 45 days a year. I have been running a supercharged VR6 engine for the better part of 5 years. I have hundreds of hours of data-logging for all parameters and I can tell you the use/need of an inter-cooler on a supercharged application are simple. If you are not going to run high boost (even on high compression) there really isn't need. I have run up to 10psi boost on a 10.5:1 CR with minimal knock on 91 octane fuel. As long as you provide reasonable fueling (my stoic in the highest boost is 12.3) then longevity will never be affected. Also, the cars you mentioned are mostly turbo-charged, and due to the added thermal load on the induced air, an inter-cooler is necessary on most turbo applications; which is contrary to the much greater efficiency of the supercharger and any thermal load to the induced air.
As Carl has stated, he is running his AF's in the very cool 11.3 range, and even though he plans to run about 7psi boost on a 11.0:1 CR, there really is no need for the inter-cooler. Also, when you add the inter-cooler, you add complexity and a greater volume to charger, as well as negatively affecting both the boost response (especially when going back on throttle after a lift) and more parts means more cost. The cost for adding the inter-cooler vs. the gain in power is not there in a low boost application.
If Carl decides to go higher in boost (like a stg II or such) then the need for an inter-cooler and more fuel tweaking would be warranted, and would provide a safer charge and more reliable power. High boost applications are more than possible IF you are willing to spend the time and money; this is contradictory to what Carl is currently working on.....of course I am speaking for myself NOT Carl.
Carl, I hope I didn't speak out of turn in your thread.
Keep up the great work!
as was stated earlier in the thread, Carl is looking to minimize cost and complexity in the kit design; both of which would be negatively affected by the addition of an inter-cooler.
I live in Las Vegas, where our average daily temps are ~ 82F, with summers running in the 100F+ range for at least 45 days a year. I have been running a supercharged VR6 engine for the better part of 5 years. I have hundreds of hours of data-logging for all parameters and I can tell you the use/need of an inter-cooler on a supercharged application are simple. If you are not going to run high boost (even on high compression) there really isn't need. I have run up to 10psi boost on a 10.5:1 CR with minimal knock on 91 octane fuel. As long as you provide reasonable fueling (my stoic in the highest boost is 12.3) then longevity will never be affected. Also, the cars you mentioned are mostly turbo-charged, and due to the added thermal load on the induced air, an inter-cooler is necessary on most turbo applications; which is contrary to the much greater efficiency of the supercharger and any thermal load to the induced air.
As Carl has stated, he is running his AF's in the very cool 11.3 range, and even though he plans to run about 7psi boost on a 11.0:1 CR, there really is no need for the inter-cooler. Also, when you add the inter-cooler, you add complexity and a greater volume to charger, as well as negatively affecting both the boost response (especially when going back on throttle after a lift) and more parts means more cost. The cost for adding the inter-cooler vs. the gain in power is not there in a low boost application.
If Carl decides to go higher in boost (like a stg II or such) then the need for an inter-cooler and more fuel tweaking would be warranted, and would provide a safer charge and more reliable power. High boost applications are more than possible IF you are willing to spend the time and money; this is contradictory to what Carl is currently working on.....of course I am speaking for myself NOT Carl.
Carl, I hope I didn't speak out of turn in your thread.
Keep up the great work!
Last edited by lsinlv; 06-02-2009 at 11:09 AM. Reason: fix gramatical error
06-02-2009, 10:11 PM
#212
Instructor
Join Date: Dec 2008
Location: bahrain
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
thanks for the input , and my comments to Carl were an atempt to evaluate the possibility of extracting the most of the 968 engine and if all the parameters are taken care by Carl,as i am sure he has everything in hand ,guess the next thing we will be waiting is the cost of the kit.
one last thing,as it was mentioned the running of AFR at 11.3 range as is visible from the dyno run ,this will not enchance bore washing, and loss of oil film strength , which will result into accelerated piston ring wear?
If a heavier grade fully synthetic oil is used , say 10-60 with more frequent changes ,will this minimise the effect?
one last thing,as it was mentioned the running of AFR at 11.3 range as is visible from the dyno run ,this will not enchance bore washing, and loss of oil film strength , which will result into accelerated piston ring wear?
If a heavier grade fully synthetic oil is used , say 10-60 with more frequent changes ,will this minimise the effect?
06-02-2009, 10:20 PM
#213
Developer
Thread Starter
As promised, I went back to the dyno today to get you guys some answers.
We wanted to know if the supercharged performance would be better or worse with the Variocam active. It was worse. The Variocam performed well and added a little more HP and a lot more torque, and increased the usable HP under the curve.
As it was designed to do.
See charts below.
Then we wanted a before-and-after supercharging dyno chart. Rather than compare a "before" chart from a different day (with different temps, air density, hunmidity, and other variables) I removed the supercharger kit while the car was strapped down to the dyno. Took less than 30 minutes, and now you have a comparison of the same car on the same dyno on the same day - within an hour of each other.
Those that know how to read dyno charts know this already... so look away while I speak to the others.
You will be tempted to compare the Max HP before with the Max HP afterwards, and do the same to the torque readings.
To do your before-and-after comparison in this way is in error.
What you want to observe is all the usuable HP and Torque UNDER THE CURVE, that is: look at the total gain (shown as area under the curve) across all RPM ranges and then you can better understand the true performance gain we have just achieved.
Lastly: I have seen a comment or two about head gaskets. Honestly, you have no reason for concern at these boost levels. I have quite a bit of experience with your head gasket as the Porsche 928 and the 968 use the same one. I have supercharged more than 40 of these cars over the last 8 years. I suppose, when I think about it - that counts as 80-some head gaskets on the V8s.
At the 5 and 6 psi boost levels we run our Stage 1 kits at, we have never had a head gasket failure. Not one. We do know the ceiling for the stock 928 head gasket is about 12 psi of boost. North of that, you need to O-ring your heads, or use a steel composite head gasket. This kit is far from needing that. You can relax about head gaskets and this kit on your 968.
This little Guinea Pig will be coming apart tomorrow so we can use these prototype parts as patterns to make the production pieces. The kit is coming together nicely, (and the car is a blast to drive). I should be able to gather my costs of manufacture and put a number to it within 30 days.
Thank you for your interest,
Carl
We wanted to know if the supercharged performance would be better or worse with the Variocam active. It was worse. The Variocam performed well and added a little more HP and a lot more torque, and increased the usable HP under the curve.
As it was designed to do.
See charts below.
Then we wanted a before-and-after supercharging dyno chart. Rather than compare a "before" chart from a different day (with different temps, air density, hunmidity, and other variables) I removed the supercharger kit while the car was strapped down to the dyno. Took less than 30 minutes, and now you have a comparison of the same car on the same dyno on the same day - within an hour of each other.
Those that know how to read dyno charts know this already... so look away while I speak to the others.
You will be tempted to compare the Max HP before with the Max HP afterwards, and do the same to the torque readings.
To do your before-and-after comparison in this way is in error.
What you want to observe is all the usuable HP and Torque UNDER THE CURVE, that is: look at the total gain (shown as area under the curve) across all RPM ranges and then you can better understand the true performance gain we have just achieved.
Lastly: I have seen a comment or two about head gaskets. Honestly, you have no reason for concern at these boost levels. I have quite a bit of experience with your head gasket as the Porsche 928 and the 968 use the same one. I have supercharged more than 40 of these cars over the last 8 years. I suppose, when I think about it - that counts as 80-some head gaskets on the V8s.
At the 5 and 6 psi boost levels we run our Stage 1 kits at, we have never had a head gasket failure. Not one. We do know the ceiling for the stock 928 head gasket is about 12 psi of boost. North of that, you need to O-ring your heads, or use a steel composite head gasket. This kit is far from needing that. You can relax about head gaskets and this kit on your 968.
This little Guinea Pig will be coming apart tomorrow so we can use these prototype parts as patterns to make the production pieces. The kit is coming together nicely, (and the car is a blast to drive). I should be able to gather my costs of manufacture and put a number to it within 30 days.
Thank you for your interest,
Carl
06-02-2009, 10:24 PM
#214
Developer
Thread Starter
Savass - no concerns about fuel washing down the cylinders, for the following reasons:
1) we normally are at 12.4 to 1 for almost the whole time under load and boost. We touch into 11.8 to 1 only at 6700 rpm. Pretty rare that you go there.
2) fuel washdown requires incomplete or no combustion. We record no such thing, there are no misfires, and the fuel is being consumed.
3) fuel washdown starts to become an issue below 10:1 AF ratio - and you can see the belching black soot out the tailpipe at that AF level.
1) we normally are at 12.4 to 1 for almost the whole time under load and boost. We touch into 11.8 to 1 only at 6700 rpm. Pretty rare that you go there.
2) fuel washdown requires incomplete or no combustion. We record no such thing, there are no misfires, and the fuel is being consumed.
3) fuel washdown starts to become an issue below 10:1 AF ratio - and you can see the belching black soot out the tailpipe at that AF level.
06-03-2009, 05:27 AM
#215
Three Wheelin'
Carl,
Looks good - if you had one for an S2 at a reasonable price I would buy one.
My only concern is how do these kits perform on the 928 when used exclusively on the track without an intercooler. Where I live it is not unusual for summer temps to hang around 95 degrees. Have you had any detonation issues with this type of use or any rod failures?
Looks good - if you had one for an S2 at a reasonable price I would buy one.
My only concern is how do these kits perform on the 928 when used exclusively on the track without an intercooler. Where I live it is not unusual for summer temps to hang around 95 degrees. Have you had any detonation issues with this type of use or any rod failures?
06-03-2009, 10:19 AM
#216
Developer
Thread Starter
At the moment, if you want an intercooled version, buy our kit when it comes out and add an intercooler.
If you are going to wait for us to develop a Stage 2 kit with intercooler for the 968, you could be waiting quite a while. We want to see what the demand is for this kit before we agree (in this economy) to spend more development monies on it.
If you are going to wait for us to develop a Stage 2 kit with intercooler for the 968, you could be waiting quite a while. We want to see what the demand is for this kit before we agree (in this economy) to spend more development monies on it.
06-03-2009, 07:23 PM
#217
Instructor
Join Date: Dec 2008
Location: bahrain
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
Thanks Carl,
very good work.
regarding the intercooler idea,my personal concern is that where we live , temps are 115-120 F,
ambient, for at least 3 months a year,even during the cooler periods track temperatures hover around 100 degrees mid afternoon.
Your statments are absolutely correct, regarding the add of an intercooler , and i guess we just have to decide if it is worth adding one as time goes by.
i presume that the kit will be complete with a dme chip to match.Can this be adjusted on individual order to suit say , a particular ambient temperature range ?
very good work.
regarding the intercooler idea,my personal concern is that where we live , temps are 115-120 F,
ambient, for at least 3 months a year,even during the cooler periods track temperatures hover around 100 degrees mid afternoon.
Your statments are absolutely correct, regarding the add of an intercooler , and i guess we just have to decide if it is worth adding one as time goes by.
i presume that the kit will be complete with a dme chip to match.Can this be adjusted on individual order to suit say , a particular ambient temperature range ?
06-04-2009, 04:37 PM
#218
Developer
Thread Starter
Our kit will NOT include a DME chip. It does not require it.
Any individual owner who has the DME chip burner and software are welcome to play with that on their own.
As a matter of course, I object to chips being burned and shipped to customers and calling them "custom chips". More harm can be done by this than good. The only right and safe way to flash and burn a chip for a car is with THAT car strapped down to a load-generating chassis dyno. Then I can customize a chip for that car safely, but the resulting chip is of no value (and quite possibly dangerous) to any other car.
You will note we are a dealer for Electromotive and market their fine TecGT system and Tec3GT systems. Either of these replace the entire LH-Jetronic fuel system and EZK igntiion system with one interlaced and dynamic system. This is a far better way to custom tune a car. Chip burning is too limited, and when done remotely, irresponsible.
But, this is probably fodder for a competely new thread.
Any individual owner who has the DME chip burner and software are welcome to play with that on their own.
As a matter of course, I object to chips being burned and shipped to customers and calling them "custom chips". More harm can be done by this than good. The only right and safe way to flash and burn a chip for a car is with THAT car strapped down to a load-generating chassis dyno. Then I can customize a chip for that car safely, but the resulting chip is of no value (and quite possibly dangerous) to any other car.
You will note we are a dealer for Electromotive and market their fine TecGT system and Tec3GT systems. Either of these replace the entire LH-Jetronic fuel system and EZK igntiion system with one interlaced and dynamic system. This is a far better way to custom tune a car. Chip burning is too limited, and when done remotely, irresponsible.
But, this is probably fodder for a competely new thread.
06-04-2009, 05:11 PM
#219
Race Car
Join Date: Jun 2003
Location: Albany, CA: celebrating 100 years of independence from Berkeley, CA
Posts: 4,887
Likes: 0
Received 2 Likes
on
2 Posts
Looks great! And what's the horizontal axis on the graphs (what's the rpm range?)
I have similar thoughts for a 968engine stuffed in a 944 body -- looks like there's going to geometry problem with headlight linkage and nose panel, and so forth.
I have similar thoughts for a 968engine stuffed in a 944 body -- looks like there's going to geometry problem with headlight linkage and nose panel, and so forth.
06-04-2009, 09:08 PM
#220
Developer
Thread Starter
what's the horizontal axis on the graphs (what's the rpm range?)
Several had asked what the supercharger was doing below 4000 rpm, so we started recording earlier to provide that answer for you. You can note that the boost starts to come in (and we benefit from it) as early as 3200 rpm. Thats a wonderfully long, not-peaky power band.
06-05-2009, 12:24 PM
#222
Developer
Thread Starter
Yes, Damian, if thats the list of mods you have already done to your car, I do not see anything that would prevent you from installing this kit.
06-05-2009, 12:28 PM
#223
Developer
Thread Starter
Pricing
The preliminary manufacturing cost reports are in.
I will start this kit at $4,295 USD retail.
That's a lower mark-up than we will use later, but that's where we will start to get some kits out there and in the hands of users.
Not taking order yet, but I should be in a position to do so in 30 days or so...
I will start this kit at $4,295 USD retail.
That's a lower mark-up than we will use later, but that's where we will start to get some kits out there and in the hands of users.
Not taking order yet, but I should be in a position to do so in 30 days or so...
06-05-2009, 01:08 PM
#224
Rennlist Member
Join Date: Mar 2004
Location: Phoenix and Forest Virginia
Posts: 1,946
Received 301 Likes
on
168 Posts
Carl- Hats off to you on a very sucessfull (if I dare say it too eairly) kit. You hit the mark on both price and application. If I do not win another 968 I am bidding on Monday I would like to further discuss buying one for my freshly restored cab. Looks and the power to back them up.. gives me goose bumps just thinking about it. I PMed you my info to discuss further.
Cheers, Mike
Cheers, Mike
