New turbo project, need advise

[las]

Hi all

I'm building a turbo engine but are having a hard time finding the right turbo and carb.

The system will be a draw through because that's what I want to build.

Specs so far:
CB alu case
8mm chromoly studs
Scat 78.8 forged crank
H-beam con rod
90.5 or 92TW barrels
Mofoco 042 heads portet and polished
Haven't decided on cam yet but would like a conservative one with no overlab and then 1,25 or 1,4 rockers
Distributor is 123ignition with map sensor
water injection / mechanical by boost

The aim is around 200-225hp in its final trim

At first I was hooked on the AJ sims Holley carb but are now leaning towards Weber DCOE, I like it's looks and heritage and endless tuning potential.

Turbo? I would love to find one that either has the carbon seal or one that its possible to install it in. It also must have an external wastegate, I want to be able to shot flames out the wastegate on full boost

It's not going to be an all out racer, but rather one that would give any HP car a good run for it's money but still be pleasant to drive around town in, that's what it wil be doing 90% of the time.
I don't think I'll need much more than 6500 rpm.

Any suggestions are most welcome......

[Dan Dryden]

If driving around town is what you'll be doing most of the time you really need to think again about going draw thru. "Draw thru" and "driveability" are words which aren't very synonymous!

[las]

Ok, that's not what I hear from others driving draw through turbos! But honestly I have no first hand experience with draw troughs.
But I can't see why I would be undriveable in town, maybe sluggish if to low compression, but it's "just" a carb.

Right now I'm looking at compressor maps and doing a little calculation on my setup trying to find a good match.

I would like to be able to run 15psi boost, that gives me a pressure ratio of around 2
With 6000 rpm the required airflow should be in the range 275 cfm or 19,25 lb/min or 0,01m3/min

It looks like the Garret GT2259 would match perfect
http://www.turbobygarrett.com/turbobyga ... 2214_3.pdf

But I would rather use the old Porsche 944 KKK K26 turbo, but from the compressor maps I can find out there it's not as suitable.......

[blue thunder]

Just some advice: Buy or build a motormanagement system and toss away the carb idea and sell the 123 ignition...... You will thank me later

The KKK K26 could work, although it is an older design and will have a slightly lower compressor efficiency compared to the more modern turbo's. What is your power goal?

Cheers,

Robin

[las]

Around 200hp with water injection.

I kind of like the carb idea you know some people just have to make all the mistakes themselves, well that's me and enjoying it along the way.
And I would like to build it old school (the 123 ignition is not I know...)

There is also the Schwitzer S2A from lowbugget, with carbon seal!

[Dan Dryden]

The carb is fine, it's the turbo causing the problem. Lots of corners (ie. Compressor fins and compressor housing and inlet manifold) for the air fuel mixture to hit and cause fuel drop out and inlet puddling. This is the recipe for stuttering and rich to lean fuel mix.
Racers get away with it because they don't spend much time running the engine at low rpm / vacuum conditions for the fuel to puddle up.
Respect that you want to make your own mistakes though.

[Chip Birks]

I had a draw through 48 dellorto setup once upon a time. I had race jets and street jets for it. Took 5 minutes to change. Race jets would load up real bad unless it was constantly being revved to clean it out. Street jets would idle nice, but it would bog when launched. With the street jets the car got 8ish mpg, which wasn't very impressive for a bug driven on the road. It drove okay, but not great.

I think if you want good drivability and draw through, go with a 4 barrel. They run on half the carb until you mash the throttle.

[brookester]

Don't expect it to run very good below about 50 degrees F. outside.
I bet a T3-60 turbo would work well.

[slowsixtyduece]

I think you are off to a good start on bottom end parts especially.

If you are looking for something pleasant to drive around town, spring for EFI. I know it can add up, but its worth it; extreme tunability, possibly ignition control plus much more if you go with a decent setup. I dont have more than $1000 into my efi setup and its almost complete! Keep an eye out for a used Megasquirt setup or even SDS. Or you can buy new; Mario @ the Dubshop has a lot of great EFI stuff.

I would try for cams such as an Engle V-26, FK-7, Web 86a on 112 LC or even something a little smaller with a little less reversion. That should get you to 6k depending on your heads, intake system, etc.

One thing to take note of: unless you already have the Mofoco heads, consider going with a more turbo specific head. This means it may have a little bigger exhaust and/or more exhaust porting. Still, there are many that run N/A heads with great results such as the CB CNC oval ports and so on. I just like to match things up as best as possible.

Im currently in the middle of my build and one thing you cannot do enough of is research! There are lots of hours you could spend just googling a topic in regards to VW turbocharging and shoptalkforums, if you havent already! One final thing, keep in mind how you want to get your compression ratio down, especially if you go with a N/A head. Most run ALOT of deck. But with your build, depending on rod length and the type of piston you use (a or b), you may be able to get a decent deck height (.040-.060") or you may have to slightly dish the pistons. It also depends on how much compression you want to run, how much boost you want to run and the rest of your combo.

[Fiatdude]

The great thing about AJ's 500 cfm carb is that it comes with a dial-a-jet -- never have to worry about having the right jets ever again. with just a screw driver and a wrench and a couple of seconds you can adjust your fuel settings -- Just have to worry about him having one ready to ship

I ran the complete MSD system on my fiat with a 2165 (with AJ's carb) and that thing was a fantastic driver -- anywhere, anytime, it was perfect!!!! Wish I had went that way on my new car rather than with the EFI system I've been fighting with for too long now

[DerrickfromNC]

Fiatdude....do you have a thread on your setup with the AJ Simms carb?

[las]

First time I planned this engine I actually bought an MS management system(but I don't want to mess with it now even though it is assembled), then decided to build it with double carbs and now I'm set on doing it draw through style. Maybe I'll change it to EFI as I go along but right now I want that big carb and turbo showing of in the engine bay..... Yes it probably would be a lot cheaper to go EFI since I have the computer, injectors etc.
So yes I have been lurking the web a couple of years on/off for this build, learning new things and forgetting even more....

I don't think a 4 barrel carb would work wonders, from what I've read they are just too big for the application.

By the way, the 123 ignition is with map sensor and is user programmable by laptop/USB so I'll have full control of timing, the possibility to do ignition stabilized idle and retard on boost.

I'm not going to look into cams right now, then my head would explode.......

I've established the bottom end and the use of 5.4" H-rods for low down torque(if you even could notice it...)

Great idea with the heads. Maybe Roy/Mofoco can put 37mm exhaust valve in the 042! That would be great, because I feel the same way and might as well get the best match in the system when ordering.

Fiatdude great to hear it can be done, I can't help feel the 500cfm would be to large for my build but the 350cfm would be spot on. From what I've read the delivery could be a problem and I did write him a few emails earlier on, asking a few questions and lastly asking for a total amount incl. shipping to Denmark, but haven't heard from him after last mail. I hate it when you have to ask a second time, or even third time to be allowed to buy stuff.
I do have to say that he asked my to phone him instead, but I'd rather do it by mail (many years gone since my last conversation in English).

Well that's one reason I'm looking into the Weber thing, besides it's looking killer with a ram flow filter. And it should be able to be fully tailored to any engine from what I've read.
But it could swing both ways!!!

What turbo did you use?

[madmike]

T3/T4 turbo
W120 cam
40 dcoe
MSD BTM so you can run normal timing around town
pulls timing out on boost very street friendly !!!!

[las]

Madmike I have a few questions if you don't mind.

Did you turbo prep the DCOE yourself, what size engine, header tubing size, well a lot of questions actually..... Stock end castings? Is the weber manifold oil heated? And of course how much boost and hp?

[Fiatdude]

Took me a while to find this video, it's from '07 LOL -- -- On the Fiat I opened up the firewall and placed the turbo and carb behind the engine -- a friend custom built the system for me

https://www.youtube.com/watch?v=dNtTvd5Qrcw