EFI to carb.... again
 

So I've read a couple of threads on this subject and several people seem to be torn.

But if one person decided to change FROM the efi to a blower with carbs.... what all would need to be changed?

I realize that person would have to measure the hatch and make any clearance issues. But what about wiring and linkage, fuel pumps, etc?

It is actually an easy swap from efi to carb. Don't know why you want to get rid of the efi. You can have a blower and still retain the efi. Anyway, I need to know a little more info, to determine what has to be changed. What engine do you currently have and what do you want to go to? What type of blower? How much power do you want? etc.
Eddie.

Thanks Eddie. I am just trying to decide what I want to do and want to know my options. I appreciate you taking your time to help. I am currently looking to buy and just trying to see what my options would be.

No problem. Like I said, if you give me a particular engine that you want to modify, then I can tell you exactly what needs to be changed. Give me a shout if you need any help, Eddie.

What engine is it? My boat came factory with the an 454EFI MPI. I had mine converted because the ecm would not except the mods. However today, there are options to solve that. I know when it was done the intake manifold came off had to add in a stock Merc HP 500 fuel pump, merc HP 500 harness bracket, new MSD ignition system and of course a Holly carb. I have the original invoice and I know there were a few little parts as with any major project.

Well I asked this because I found some 250 blowers with carbs and everything for a pretty good deal. The motors in question are 502efi's. The Prochargers for these things would be close to 9.5k. I could get the blowers and carbs for half that. SO it got me to thinking.... and I thought who better to bounce ideas off than you guys!!!

Remember I dont have anything yet.... I just want to make sure I do the right thing the first time out. I am old school carb guy, so tuning and rebuilding, etc is second nature for me. But the Prochargers are suppossed to be a bolt on deal with no computer mods and they DO have intercoolers.

Trying to decide if I am just being cheap or if I should do what I am familiar with?

If you happen to go the Procharger route, you will need to reprogram the ecm. I realize they say you don't need to, but if you want the thing to be reliable and not soot the transom and foul plugs everytime out, then the ecm needs to be touched up some. Just keep that in mind if you go that route. The 250 blower would be a pretty simple deal to do. I take it they don't have intercoolers. You could always add them later, but you would have to keep the boost down low until you did.
Eddie

I am currently doing a 500efi with a roots blower. I just purchased two holley throttle bodies and spacer plates( which is where the injectors will be mounted) so the fuel will enter above the blower.

Bigger injectors,fuel pump, filter,cooler and custom fuel rails and lines. It will be reprogrammed on the dyno.

Result should be a 800hp, easy starting, idling and clean running fuel injected motor with the benefit of knock protection. Why go carb when FI is so much nicer?

Eddie,
Right on.... I thought you would have to reprogram the ecu. Just another strike against the efi in my book. What are the chances of actually getting them right the first time?? :hitfan:

EFI is great for fuel economy and idle on cars. As for power, carbs will make the same power at WOT but will always be easier to work on IMO.

Man I love the compact package of the prochargers and the intercoolers, but the ease of tuning and such is a big plus for the 250 blowers. Now the downside to the 250 is two-fold
1. No intercoolers and 2. Clearance under the hatch.

The ECM can be reprogrammed by guys like Eddie. I have had it done and the end result was very turn key. My boat actually ran better than stock when I had a Procharger and reprogrammed ECU.

I got it all set up, sent off my ECU on Monday, got it back on Friday and put it in that afternoon.

On a proven setup like that, we are almost certain to get it right on the first try. There are quite a few of us who have done that setup many times on a stock motor. Modified engines take a little more work and should be done on a dyno to get the best tune possible. We have a program for the stockers and just need to dump it in and go.
The biggest benefit of the efi is safety. With knock protection, you have a huge safety margin that becomes much more crucial in boosted applications. Although the carb is simplier, it gives up that protection. That could mean the difference of beating the bearings out of the bottom end or not, should you get some cheap fuel. Also, you just get a better overall engine. You have basically unlimited tunability, allowing you to tune it to the nth degree.
Eddie

Well I definitely appreciate the help Eddie. You'll be the one I call for this if it works out this way.

My pleasure. Give me a shout if you have any further questions.
Eddie

Another option is get the Prochargers and convert to blow a blow thru set-up...that is if you wanted to go carbed. I know you know Mustang Billy he can set you straight on a blow thru setup. Also I have a buddy here that is a Procharger dealer.

Rock on..... I think I've met Billy before. Nice guy.

The shop that sponsored my car is a procharger dealer and can get me some awesome deals. But it would still be around 9k whereas the 250 blowers with carbs and everything for around 5.5k.

But in all honesty, if I get a boat that has efi, I'll use the prochargers. Carbs and I'll do the blowers.

Speaking of your car...You made any more hits? If that thing doesn't sell before May you need to come to St. Louis for WSC1.:D

Havent made anymore hits yet. Might have a buyer this weekend, but still not sure. If not, I'll be running it the next few weeks here at Baytown.

Watcha runnin?

Its an Outlaw 10.5 Mustang. Single turbo alcohol efi. Havent been making any hits cause I am trying to sell it, but the market for expensive race cars isnt so good right now. So I'll be taking it out in a few weeks to make a few more shakedown runs.

Sweet! We were running outlaw 10.5 in an '81 Malibu. Were you in Vegas in November?

Nah. Just had a baby and the car is basically new. Only has 4 passes, so I need a few more passes before it will be ready for competition.

The potential of the blown alchy efi is unbelievable. This a buddy who runs a prostreet mustang up here..

http://plustest.no-ip.org/Qstore1/Qstore.cgi

Dal Sangha breaks Les Davenport's ProMod engine dyno in BC with over 2500(est.) Horsepower, and over 1800lbs of Torque with his twin Precision/GT88 small block!

:evilb:

The guy who tunes my car actually did some tuning on Dals car.

It's a small, small world... :D