FPrep2ndGenRX7

Or atleast I'm going to try. On my FP car I'm initially going to be running a Weber 45DCOE sidedraft using the racing beat upper intake on the stock factory lower intake. The actuators have been removed from the lower intake and the sleeves are also removed(no flaming please, it was that way when I got it).

I'm planning on one dyno trip to tune the carb if needed but it shouldn't need to much tuning. With a hard copy in hand I will have the base line for comparison to the FI upgrade I'm planning.

I have found a Weber 45 DCOE throttle body for FI that I will use to replace the carb at a latter date and make another trip to the dyno for tuning. I'm planning on keeping the 81-85 distributor for ignition and using an EM-3 by SDS to control the fuel delivery. This should be a good comparison since the runner lengths and throttle bore sizes will all be the same as well as the ignition being set the same. I'll be using the same engine for both setups also.

I'm hoping to have some solid proof of FI being the way to go and put an end to the constant bickering that happens ever few weeks here on the forum. Wait a minute. I actually like reading the post of people bickering as I find it amusing. Maybe I should keep my findings to myself and share it with a few people that share my views of it. NZConvertible would probably appreciate my findings.

Let the bickering begin!

Icemark

Perhaps you should also dyno the motor before the carb/FI change, with the stock CAS/dist and stock FI.

That way you'll have a real baseline to compare too

FPrep2ndGenRX7

Can't do that as the motor is already on the engine stand awaiting install into the FP car. Previously the motor was in The Parts Trader Project Car. It is a strong running stock engine. Once installed I'll do a compression test just for the numbers and one again later before the FI dyno runs.

Icemark

ahhh I figure it was something like that, but I was hopeing, Oh well.

RETed

I don't see what this will accomplish.

My points on the advantages of FI were gas mileage and driveability.&nbsp Both of which cannot be qualified nor quantified with a bunch of dyno runs.

You can tune WOT on a carb to match FI power output no problem.&nbsp WOT power is just one very small aspect of a "properly running engine".



-Ted

FPrep2ndGenRX7

I'm on a limited budget so I have to start with what I have. What I have is a carb loaned to me from a friend that couldn't use it with his supercharger. He had to go FI. I simply have a chance to do a little before and after testing that will hopefully help others trying to make a decision on whether to use a carb or FI. With the constant debates about the two setups I would like to see the differences first hand and be able to document those with dyno sheets and my observations autocrossing the car with the carb and FI. I will also have a co-driver with years of experience to voice his opinions about each setup. Eventually I will have a page about my car and the growing pains of getting it running and the changes it has gone thru.

Will this end the debates we have on the forum? No. Its fun to argue on the forum as long as it doesn't get stupid and insulting. I've learned alot from many of the forum members and wish to continue my learning with hands on experience.

RETed

Agreed.&nbsp Good luck with the racing and the car!


-Ted

FPrep2ndGenRX7

Thanks!

Kurgan

Yes, good luck with the racing and the car... but there is no comparison between a properly tuned FI car and one running on a carb. The FI will always be the better route (not cheaper, but better in driveability, tunability, streetability and any other -ability you can think of... except ineffecientability )

NZConvertible

Is that a limitation of the class you're racing in? That 45DCOE carb is far too small for a 13B, and like Ted said, I don't think you'll see much gain going to the 2x45mm TB. That's smaller than the stock TB by a third! The EFI TB will outflow the carb though, because there're no chokes or jets in the way. If you can, go for a bigger TB, at least 50mm if you can get it, which will flow ~20% more than the 45mm. One if EFI's many advantages over carb is that a larger TB doesn't cause driveability problems like a big carb does, and even on a racetrack, that's important. Looking forward to it!

tims

yes a better setup for the fuel injection system is to use the stock second gen manifold and if rules allow a four port turbo II manifold. a very competitive nationally run E-production car here in Southern California is making over 200HP to the rear wheels using Motec and the stock N/A second gen manifold. the distributor ignition and relatively small 45mm throttle body will limit max power. our 13b PP motor is using two 55mm throttle bodies.

FPrep2ndGenRX7

I realize that FI is superior to a carb. The reason I'm starting with a carb is its free. A friend has loaned it to me till I get my FI setup. I just have a chance to do some before and after comparison of the two and report back about it. I'm positive the FI will be better for my application as drivability is important in autocross. WOT is fun but when exiting a turn at lower than desired rpm I want it to work the best that it can and FI is the only way to go.

FPrep2ndGenRX7

There are some limitations but I'm not close to the max carb size. This carb is the standard setup you could buy from racing beat (dellorto's for them) or Mazdatrix and maybe in the Victoria British catalog. The throttle bodies for the FI setup come in either 42mm or 45mm. Nothing bigger or I would probably get them. I realize the factory TB is bigger but when combining that with the rest of the factory intake its much heavier than the carb or TB setup using the Racing Beat upper intake piece. I'm sure the weight difference is not made up for with the smaller TB but I can make my car weigh less alot easier than I can afford the HP. I can get the Weber 45 TB for $250 from www.piercemanifolds.com. The same thing by TWM cost almost $500. Yes I would rather have the TWM pieces but money is tight so I have to get what I can when I can.

After reading what I just typed I confused myself. I'm sure you guys might be confused after reading it. I might add more later if anyone wants clarification. Thanks for the input guys in trying to keep me straight. I really appreciate it.

NZConvertible

This must be the only case of the American market thinking smaller than everywhere else! Here and in Australia 95% of carb’d rotaries are using a Weber 48IDA, or one modified to be even bigger. The PP guys like to use 51IDA’s! Aftermarket Weber-style throttle bodies are available from 2x40mm, but 2x50mm is the most popular in rotaries. Maybe you should contact some of the Australian rotary and performance workshops.

crossbar17

mmm

FPrep2ndGenRX7

Thanks NZ. Don't forget I'm using a stock port S4 engine. Do you think that the 50mm TB will help in that application or do you really need a ported engine to take advantage of the larger TB?

RacerXtreme7

iTrader: (2)

I've got a DCOE / DHLA TWM throttle body for sale with dual 50mm throats. Its the highest quality t/b available. I have the fuel rails, extentions, hardware, seals, and air horns, all BRAND NEW. It is not the downdraft but is the side draft the replaces exactly what your talking about. I had the Dellorto system on my ported 6port and was going to convert to t/b while running a Wolf EMS, but I have moved on to BOOST and am currently building a series 5 turbo motor with a 3rd gen upper intake and t/b and no longer need the TWM t/b.

FPrep2ndGenRX7

One quick correction. The carb a freind is letting me borrow is a 48 DCOE. I'm not sure where I got 45. Anyway, the carb is closer to the correct size.