To carb or not to carb

Sterling · 03-20-2008, 08:23 AM

"Rx-7s don't allow for flight." is another statement which I'll stand by.
Can you fly one?
Why sure you can; if you drive it off a municipal parking building roof.
Can you figure out how to make an intercooler work with a draw through setup? Yes, of course you can. You can ALWAYS figure out how to make something work, but usually the cost in time and or money makes it prohibitive.
If it were an easy task, it would be the "norm". I'll go out on a limb here and suggest, without even having seen it yet, that the trouble gone through to get it to work in the examples you cite was far beyond the work to have gone the route of a traditional intercooled blow through system. I'll even go as far as to say that the performance gained from getting the draw through to work with an intercooler over using the same components in an intercooled blow through setup, if any at all, probably didn't justify the extra effort in time and expense.
I myself am not partial to either, and I plan on getting a large Camden for a streetported 12a, running my carb, and water injection at high boost. I very much celebrate ingenuity and the work and efforts people make to try new things or improve on things. But for the purposes of illustrative comparison, "no", draw through systems GENERALLY don't allow for an intercooler.

85rx-7gsl-se · 03-20-2008, 08:49 AM

Quote:

Originally Posted by nolimitind

I beg to differ. It all depends upon how you locate the charged/compressed air. I personally know of two guys that are running turbo'd 4-port 13Bs with RB Holley 4777s with FMIC. We built a custom "plenum" and placed the compressed air underneath the carb. It didn't make a whole bunch of sense in the beginning, but after plenty of study on turbo setups, it made total sense. I will try and find the source that explained everything so clearly. I know I bought the book at Books-a-mil......some building turbo systems, or something of that nature.

From everything I read on turbo systems...Intercoolers after the carb should be avoided as the intercooler is exposed to air/fuel rather than just air like most setups and the fuel from the mixture can become trapped or puddled in the intercooler.

jtbshaw · 03-20-2008, 12:34 PM

You can get oil from a blown seal in the I/C, but not fuel. The "cold" side of the turbo is nothing more than a compressor. There is no fuel/air mix running through a "conventional" setup.

Sterling, it was actually a simple setup. It looked akward, but it was very functional and didn't cost much (some aluminum sheet and 2 Holley 1/2" base flanges...metal of course).

On the Camden, I loved the ones I have owned. The only thing that most overlook, especially in the South where I am, is the cooling issue. Most don't address this until after the Camden has been installed and see the extra heat generated by the blower. The turbo setups that i have mentioned remained somewhat close to stock cooling due to the I/C cooling the charged air.

Look, guys, I'm not trying to say any of us are wrong or picking fights. There are just a select few people I know that like to have something different. The rotary is the 1st thing (there's not that many around here), and then anything else adds to that. I hope I haven't offended anyone, as that was not my purpose. Just as Sterling mentioned, these are rare cases of ingenuity and against the grain methods of making their system work. I was priviledged to have a small part in it.

85rx-7gsl-se · 03-20-2008, 12:53 PM

Oh, so you are just running the pressure under the carb? Most of the setups I saw mounted the carb before the turbo inlet, drawing gas through the turbo...these setups would result in fuel in the intercooler.

jtbshaw · 03-20-2008, 01:05 PM

There you go, I guess I finally explained it so that it could be understood. The system that you mention is very inefficient and I think that's what Sterling was bringing up that the gains were not worth the work involved or cost.

Yes, a custom plenum/chamber underneath the draw through carb allowed the system to fully function with the I/C. I even have a Camden manifold here that I planned to build the same setup for a IDA, but couldn't locate phenolic floats anymore for the IDA. The boost would crush the stock IDA floats, therefore needing a different material. I could be backwards since it has been almost 2 years since I was inside the IDA. It either has brass floats - stock, and needs phenolic for boost, or the other way around. Regardless, no one seems to make the floats needed for boost for the IDAs. Or at least to hold more than 7-8 psi. I was looking for something to hold up to 20-24 psi.

85rx-7gsl-se · 03-20-2008, 01:18 PM

Sounds cool. I re-read your post and it actually pretty clear, but the idea was kinda out there so..... My bad

jtbshaw · 03-20-2008, 02:24 PM

No problem. This ain't the first time I've had someone say that something that I've done is kind of out there. A lot of what we do is one off custom stuff. I just got back from a new client's home. Fuggin' 17,000 sq. ft. home with a built in movie theatre and 2 bay car wash. We get to build his custom stainless steel drop boxes for the in-home pressure washer system that we sell also. 2 weeks ago, we got the order to build 2 custom winch boxes for Dale Jr.'s new car trailer and his team mate Casey (sp? - I'm not a NASCAR fan) Mears' trailer, out of 1/4" aluminum plate. Now we are making Evo parts. Next week we will probably do a production run on our patented stuff......I love what I do.

Anyway, sorry to get off topic. Didn't mean to trash your thread Fikren. I love carbs. Glad we have someone like Sterling to work on/mod the Nikkis. IDAs have been my preference for many years.

jgrewe · 04-06-2008, 09:03 PM

I go EFI if given the choice. The biggest issues we run into is rules between carb and EFI. We can run a 48IDA or even a 50DCOE w/42mm chokes on any manifold or we have to run the entire stock intake system with any stand alone. The RPM's we run cause trouble with the stock intake runner lengths and the IDA set up is better above 8000 rpm. I'd rather be looking at number values on a laptop than a box of jets and e-tubes etc.
If you like to tinker with electrical stuff instead of carb stuff a Megasquirt can be set up very cheaply with almost all stock parts. The stock injectors on an FC will feed 250hp no problem. If you are running on the street the stock manifold is pretty good for driveability, how much time do you spend above 8K on the street anyway? Maybe half the time at most

04-06-2008, 09:03 PM	#23
jgrewe Rotary Fan in Training Join Date: Feb 2008 Location: On the Beach iTrader: (0) Posts: 59 Rep Power: 17	I go EFI if given the choice. The biggest issues we run into is rules between carb and EFI. We can run a 48IDA or even a 50DCOE w/42mm chokes on any manifold or we have to run the entire stock intake system with any stand alone. The RPM's we run cause trouble with the stock intake runner lengths and the IDA set up is better above 8000 rpm. I'd rather be looking at number values on a laptop than a box of jets and e-tubes etc. If you like to tinker with electrical stuff instead of carb stuff a Megasquirt can be set up very cheaply with almost all stock parts. The stock injectors on an FC will feed 250hp no problem. If you are running on the street the stock manifold is pretty good for driveability, how much time do you spend above 8K on the street anyway? Maybe half the time at most __________________ New rat from the sinking ship.

03-20-2008, 08:23 AM	#16
Sterling Premium Vendor Join Date: Feb 2008 iTrader: (2) Posts: 74 Rep Power: 17	"Rx-7s don't allow for flight." is another statement which I'll stand by. Can you fly one? Why sure you can; if you drive it off a municipal parking building roof. Can you figure out how to make an intercooler work with a draw through setup? Yes, of course you can. You can ALWAYS figure out how to make something work, but usually the cost in time and or money makes it prohibitive. If it were an easy task, it would be the "norm". I'll go out on a limb here and suggest, without even having seen it yet, that the trouble gone through to get it to work in the examples you cite was far beyond the work to have gone the route of a traditional intercooled blow through system. I'll even go as far as to say that the performance gained from getting the draw through to work with an intercooler over using the same components in an intercooled blow through setup, if any at all, probably didn't justify the extra effort in time and expense. I myself am not partial to either, and I plan on getting a large Camden for a streetported 12a, running my carb, and water injection at high boost. I very much celebrate ingenuity and the work and efforts people make to try new things or improve on things. But for the purposes of illustrative comparison, "no", draw through systems GENERALLY don't allow for an intercooler.

03-20-2008, 12:34 PM	#18
jtbshaw ORD - Old Rotary Dude Join Date: Feb 2008 Location: Pelham, AL iTrader: (3) Posts: 319 Rep Power: 17	You can get oil from a blown seal in the I/C, but not fuel. The "cold" side of the turbo is nothing more than a compressor. There is no fuel/air mix running through a "conventional" setup. Sterling, it was actually a simple setup. It looked akward, but it was very functional and didn't cost much (some aluminum sheet and 2 Holley 1/2" base flanges...metal of course). On the Camden, I loved the ones I have owned. The only thing that most overlook, especially in the South where I am, is the cooling issue. Most don't address this until after the Camden has been installed and see the extra heat generated by the blower. The turbo setups that i have mentioned remained somewhat close to stock cooling due to the I/C cooling the charged air. Look, guys, I'm not trying to say any of us are wrong or picking fights. There are just a select few people I know that like to have something different. The rotary is the 1st thing (there's not that many around here), and then anything else adds to that. I hope I haven't offended anyone, as that was not my purpose. Just as Sterling mentioned, these are rare cases of ingenuity and against the grain methods of making their system work. I was priviledged to have a small part in it.

03-20-2008, 01:05 PM	#20
jtbshaw ORD - Old Rotary Dude Join Date: Feb 2008 Location: Pelham, AL iTrader: (3) Posts: 319 Rep Power: 17	There you go, I guess I finally explained it so that it could be understood. The system that you mention is very inefficient and I think that's what Sterling was bringing up that the gains were not worth the work involved or cost. Yes, a custom plenum/chamber underneath the draw through carb allowed the system to fully function with the I/C. I even have a Camden manifold here that I planned to build the same setup for a IDA, but couldn't locate phenolic floats anymore for the IDA. The boost would crush the stock IDA floats, therefore needing a different material. I could be backwards since it has been almost 2 years since I was inside the IDA. It either has brass floats - stock, and needs phenolic for boost, or the other way around. Regardless, no one seems to make the floats needed for boost for the IDAs. Or at least to hold more than 7-8 psi. I was looking for something to hold up to 20-24 psi.

03-20-2008, 02:24 PM	#22
jtbshaw ORD - Old Rotary Dude Join Date: Feb 2008 Location: Pelham, AL iTrader: (3) Posts: 319 Rep Power: 17	No problem. This ain't the first time I've had someone say that something that I've done is kind of out there. A lot of what we do is one off custom stuff. I just got back from a new client's home. Fuggin' 17,000 sq. ft. home with a built in movie theatre and 2 bay car wash. We get to build his custom stainless steel drop boxes for the in-home pressure washer system that we sell also. 2 weeks ago, we got the order to build 2 custom winch boxes for Dale Jr.'s new car trailer and his team mate Casey (sp? - I'm not a NASCAR fan) Mears' trailer, out of 1/4" aluminum plate. Now we are making Evo parts. Next week we will probably do a production run on our patented stuff......I love what I do. Anyway, sorry to get off topic. Didn't mean to trash your thread Fikren. I love carbs. Glad we have someone like Sterling to work on/mod the Nikkis. IDAs have been my preference for many years.