Turbos and BlowThru Carbs

[TC]

So with all this talk about Turbo's, I'm thinking of changing my idea of a Junkyard nitrous motor(which I've already done) to a Junkyard motor using one of these turbo kits off Ebay. But instead of having to deal with the hassle of EFI and the headaches of tuning it I figure the fastest and best way would be going with a BlowThru Carb.

Now normally on a naturally aspirated 350 I would run a 750 cfm carb, but doing a turbo motor would you want to increase the Carb size?? Like go up to an 850??

Also I saw BlowThru carbs on EBay for 5-600 bucks, opinions??

[A/Fuel]

Re: Turbos and BlowThru Carbs

The bigger carb will flow more right? LOL!!!!!
Just do it.....I dare ya!

[milner351]

Re: Turbos and BlowThru Carbs

I've been thinking along the same lines (the ranger headers where cheap enough) ;D

I would try to find someone who's built a blow through on the same size engine and see what they are running.

I don't know how boost effects flow rates in relation to engine size/pumping loss/volumetric efficiency
- the cfm ratings are done at a constant pressure across the venturi's - so obviously boost changes everything.

[STINEY]

Re: Turbos and BlowThru Carbs

2 words - - Modulator Rings.

Nobody seems to know what they are or what they do for carbs under boost.

[joe_rocket45]

Re: Turbos and BlowThru Carbs

I think the idea is to go with a slightly smaller carb to boost signal to the boosters plus the restriction helps cool the charge slightly (but to me that's only b/c the restriction makes heat pre carb, right?)... anyways do not try to over carb a blow through setup

[88 Dippy]

Re: Turbos and BlowThru Carbs

i have been having the same idea with my LeBaron. the stock fuel system is none tunalbe so you have to buy a stand alone or MegaSquirt.

but i am cheap i just want to put a turbo on it and a carb lol :D the stock ECU would still controle timing if i left th injectors pluged into the connectors it would be so redneck though ;D

[BangShiftChad]

Re: Turbos and BlowThru Carbs

Several guys on here are fans of blow through carbs. I have seen blow through setups run perfect almost half as often as I've seen them run like crap. LOL ;D ;D ;D ;D

I think the safer solution is to use a box instead. Like a Vortech box. The carb doesn't know it's under boost that way, and it's always happy. We've run the Camaro that way, and still do, and it works great.

But, I've known guys that ran less than 10 pounds and just did a hat on a regular carb.No tricks.

[dieselgeek]

Re: Turbos and BlowThru Carbs

I vote for the box! Freiburger had that blower motor running like a champ with the carb box... he said it was totalyl easy to do too. I trust him.

and, I think it's pretty clear that a blow-thru carb with anything more than low boost is far more rocket science than any EFI setup - and a heluva lot less forgiving, there are *experts* who have a single mishap (oops, ran a few psi too much boost) and burning holes in expensive parts.

But, anything that gets TC off the keyboard and into a running car, I'll support no matter what it runs! haha

[TC]

Re: Turbos and BlowThru Carbs

So what I'm hearing is run the same size carb that you would run naturally aspirated, but use a carb box instead or a blowthru carb.

[seanm]

Re: Turbos and BlowThru Carbs

No need to go to a bigger carb for a blow- through. The same or a little smaller is fine. 750's have supported 1000hp+.

Most use a bonnet, and that is what most guys that use blow-through know about. The box isn't as popular. Have never used one. But it might work great.

The carb will need to be modified and tuned, so you can't get away from that. There is a lot to learn and more than one way to modify a carb to work with boost.

This is a basic guide to building a blow through carb: http://www.hangar18fabrication.com/blowthru.html

It covers the basics only. That may be all you want, depends on how "perfect" you want to be.

and, I think it's pretty clear that a blow-thru carb with anything more than low boost is far more rocket science than any EFI setup - and a heluva lot less forgiving, there are *experts* who have a single mishap (oops, ran a few psi too much boost) and burning holes in expensive parts.

Oh blessed goddess of speed, lets not turn this into another carbs vs EFI thread.

In what way is a carb for high (please define) boost "rocket science"? Have you built carbs for blow-through? Thats an honest question? Would like to know your experiences good and bad with blow-through carbs.
Have seen EFI cars tuned by "experts" with burnt parts too. So EFI and carbs both can suck ;)

[dieselgeek]

Re: Turbos and BlowThru Carbs

In what way is a carb for high (please define) boost "rocket science"? Have you built carbs for blow-through? Thats an honest question? Would like to know your experiences good and bad with blow-through carbs.
Have seen EFI cars tuned by "experts" with burnt parts too. So EFI and carbs both can suck ;)

Do you read Speedtalk forums Sean? Look at the details thoseguys are going through for blowthru carbs. Any person would be CRAZY to even think of implying that an EFI system is more complicated. And, if they did, that person would need to remember that "EFI" actually means "Powertrain Management" - take away all the extras that EFI gives you - say you're running a "fuel only" EFI system, not timing, not fans, not fuel pump, no barometric corrections, no datalogging - the EFI system is FAR less complicated, and FAR Less "guesswork." There are guys with very fast blowthru cars arguing different methods for accomplishing the same thing - it's not just rocket science, it's voodoo art.

Guys that pretend a 30psi carb is no big deal - I question. There's one guy on here who I would let build me one, that's Camaro Eric. He builds/sells them professionally - and even he had a mishap when their boost control went nuts and burnt holes in pistons on one of his friends' cars. I've never had that happen, not once, and I'm 1/100th as skilled as Eric at *anything* car related.

I read the megamanual, I followed the directions, I was patient and asked questions when I got stuck, I didn't piss and moan, and we ended up with Parish's truck. It was reliable as OEM. Now, add in all the extra features we were controlling on it: nitrous to spool the turbos, meth injection, datalogging, baro corrections, boost control...
this may not be a carb-vs-EFI discussion, and I have nothing against carbs - but I think it is a bit "out there" to say it's just as easy to build/tune a carb setup for 20-30psi as it is to implement the electronic version of the same thing (a fuel-only EFI control).


edit: all that being said, I enjoy reading about how the voodoo works, so... don't let me convince TC he needs to do a EFI setup. lol

[CDMBill]

Re: Turbos and BlowThru Carbs

I think we had a box vs. hat thread here soem time ago and hopefully someone with greater site navigation skills and time than I have can dig it up.

My only boosted experience is with a box so I can speak to its simplicity once you get past the purchase price and increased cost of plumbing. My and I wnet that route because of a series written in Car Craft about a Vortech blown BBC that eventually made 900+ hp IIRC. Its a 466 BBF but it runs like a watch and he hasn't had to touch the tune in two years after we set it up with my AFR unit.

For these lower pressure 'junk' deals I think a blow through would be 'cheaper' by a samll amount and there are several articles out there dealing with building your own blow through carb. Like the recent CC cheap turbo article its seems the two things you wouldn't want to skimp on are the carb itself and the waste gates.

Share pictures of the builds guys.

[seanm]

Re: Turbos and BlowThru Carbs

Do you read Speedtalk forums Sean? Look at the details thoseguys are going through for blowthru carbs. Any person would be CRAZY to even think of implying that an EFI system is more complicated. And, if they did, that person would need to remember that "EFI" actually means "Powertrain Management" - take away all the extras that EFI gives you - say you're running a "fuel only" EFI system, not timing, not fans, not fuel pump, no barometric corrections, no datalogging - the EFI system is FAR less complicated, and FAR Less "guesswork." There are guys with very fast blowthru cars arguing different methods for accomplishing the same thing - it's not just rocket science, it's voodoo art.


edit: all that being said, I enjoy reading about how the voodoo works, so... don't let me convince TC he needs to do a EFI setup. lol

Who said carbs were better than EFI or easier to tune at 30 psi? Definitely not me. They both suck, IMO. ;D When they build a $50 dollar bolt-on part that can make 3000hp and tune itself with 0-400psi I'll be happy.

Have been on Speedtalk, what you see about carbs I've seen about EFI. I see guys posting about all the crazy problems and tuning difficulties they have with EFI (personally dealing with it now, as you know) and it looks about the same as the carb guys to me. They each use different terms, but have the same problems.

So have you built or tuned blow-through carbs? That was my question. What you posted before sounded like personal experience and led me to believe you had done some carbs to. Who is Camaro Eric? Would like to know more about his work.

Either way, will TC ever get this done? ;D

TC: On the carb, you can do it yourself if you want to take the time to learn. Or have someone do the carb. If your looking for 10-15 psi and don't mind playing with it, do it yourself, IMO. It may not be perfect, but it should run decent if you know your way around a carb.

I don't know about the blow-throughs on Ebay. There are a few places that have done well with them if you want to have a carb professionally done. But that goes against the cheap side of it.

CSU: http://www.csucarbs.com/

C&S: http://www.candsspecialties.com/

Brent Davis is also well respected for his blo-thru carb work.

[dieselgeek]

Re: Turbos and BlowThru Carbs

So have you built or tuned blow-through carbs? That was my question. What you posted before sounded like personal experience and led me to believe you had done some carbs to. Who is Camaro Eric? Would like to know more about his work.

I've only rebuilt and tuned carbs on my Kohler engine'd lawnmower, my 350cc Yamaha quad, my neighbor's straight six flattie tractor (before we TBId it). So no, haven't done it.

But I never see EFI discussions on Speedtalk, nobody there does EFI except for 3 or 4 guys? I definitely see more talk about carb tuning and, I think there's no doubt it's voodoo meets rocket science.

[TheSilverBuick]

Re: Turbos and BlowThru Carbs

Who is Camaro Eric? Would like to know more about his work.

Eric68 on the forums here. Does some interesting fine tuning on carb's.

http://www.bangshift.com/forum/index.php?action=profile;u=32