Turbo weber 32/36 questions(blow through)

Engine, Transmission and related drivetrain.
jwerty1
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Joined: 02 Sep 2013 10:56

Re: Turbo weber 32/36 questions(blow through)

Post by jwerty1 »

Well, just made my own msd 8mm plug wires and hooked up a new coil to go along with the new msd 6a box. Also checked my compression and it's 180-190 across the board, woohoo
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bertvorgon
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Re: Turbo weber 32/36 questions(blow through)

Post by bertvorgon »

That is very good, at the height of my Slaloming, and the way we set my cam up, I had 210 for cranking pressure. I had to run full on race gas when racing, but, it kept me competitive with NA cars on the slow speed corners, where I needed that off boost torque.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer
jwerty1
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Re: Turbo weber 32/36 questions(blow through)

Post by jwerty1 »

Keith, another question for you. I installed a new turbo because my exhaust seal was blown. However, in 2nd gear I will spike about 20psi then it will taper off to around 15. 3rd gear and up the boost spike decreases to about 15psi and then tapers down as well. It's internally gated and I was wondering why I am seeing the pressure drop. I can unhook pressure to the wastegate and nothing changes. I know this turbo is capable of more boost than that, but it won't do it. I haven't done a boost leak check, but I know that if I have any they are quite small as I can not hear the tell tale sign of a boost leak. Any ideas what could cause the low boost? Seems weird to me that it tapers off so badly, normally exhaust/wastegate issues would cause
Boost creep.
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bertvorgon
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Re: Turbo weber 32/36 questions(blow through)

Post by bertvorgon »

Hmmm.... that is a funny one. Makes me wonder if something is still restricting flow.

Try just defeating the waste gate and see what happens.

Leaks must be determined also, you just never know. We used to say a .002" leak at the airbox was not acceptable.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer
jwerty1
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Joined: 02 Sep 2013 10:56

Re: Turbo weber 32/36 questions(blow through)

Post by jwerty1 »

Well, from changing from the l18 to l20 the doe pipe outlet changed a bit and I had to mangle it to fit. So I made a new do would but still the same issue. I'll have to make a boost leak tester and go from there. However, I am still very pleased for a home built turbo kit. Working on front disc brakes right now
dislexicdime
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Joined: 09 Aug 2004 18:26
Location: tigard oregon

Re: Turbo weber 32/36 questions(blow through)

Post by dislexicdime »

Is the waste gate arm adjustable?
L series only have one header!

i need another garage mine is full of part's
jwerty1
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Re: Turbo weber 32/36 questions(blow through)

Post by jwerty1 »

The wastegate arm is adjustable
dislexicdime
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Re: Turbo weber 32/36 questions(blow through)

Post by dislexicdime »

Can you find the adjustment specs? I had a starion and if you didn't have it adjusted right it would Cause the boost to fluctuate .
L series only have one header!

i need another garage mine is full of part's
stanis82
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Re: Turbo weber 32/36 questions(blow through)

Post by stanis82 »

bertvorgon wrote: 19 Jun 2014 11:17 Yup, books are one thing....nothing like the real world experience...at least your engine is still in one piece. Here in Vancouver, back in the 70's, more engines were blow up with turbo's on them , than you can imagine.....there was no knowledge base then...kind of a black magic world.

One of our friends is GTR certified also, just took a look at my G35 brake issue.
Keith i sent you a PM.. Time to get this post back up!!
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bertvorgon
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Re: Turbo weber 32/36 questions(blow through)

Post by bertvorgon »

Hey Teran, welcome back!

Wow, time has flown since this post started. You are on the right path for sure, don't know if I can help much as you are on a path the is a new frontier, blowing through 2 carbs in a drag application.

First thing for sure is make sure fuel delivery lines can deliver the VOLUME required. As mentioned, at one point I had that 3.0 MM needle and seat, which I ultimately did not need and went to a 2.5 MM needle. It turned out that was my learning curve to have enough VOLUME of fuel.

I too milled the top choke plate area down, to increase air flow in my air box. You can see in the picture the amount taken off.

Only testing will tell if sealing off the secondary air is a good idea or not. Do you have a wide band to monitor the A/F ratio? I know at one point my main fuel secondary jet was just over 3.MM. Many, Many years ago, a fellow showed up with a turbo Fiat X19, running a 32/36 and he ran it with NO FUEL JET in the secondary!

We did bore out the secondary, enough meat to take a good cut, then do a back cut to regain a "venturi" effect. That really increased the air flow.

Make sure you are using the right top gasket of course. Picture attached of the 2 available. For what it is worth I put the bearing kit in also, makes the carb very smooth in actuation.

Make sure, if you can with your compressor bypass valve, that it does NOT pull open till at least 16" or more of vacuum, as that keeps the boost up when shifting as much as possible.

Float change for sure.

I had a 1982 SR5 with the 3TC motor, I loved it as that was a torquey motor!

Not much else I can add at this point...keep us posted on progress.
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"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer
stanis82
Posts: 15
Joined: 23 May 2018 07:02

Re: Turbo weber 32/36 questions(blow through)

Post by stanis82 »

bertvorgon wrote: 16 Jun 2020 09:51 Hey Teran, welcome back!

Wow, time has flown since this post started. You are on the right path for sure, don't know if I can help much as you are on a path the is a new frontier, blowing through 2 carbs in a drag application.

First thing for sure is make sure fuel delivery lines can deliver the VOLUME required. As mentioned, at one point I had that 3.0 MM needle and seat, which I ultimately did not need and went to a 2.5 MM needle. It turned out that was my learning curve to have enough VOLUME of fuel.

I too milled the top choke plate area down, to increase air flow in my air box. You can see in the picture the amount taken off.

Only testing will tell if sealing off the secondary air is a good idea or not. Do you have a wide band to monitor the A/F ratio? I know at one point my main fuel secondary jet was just over 3.MM. Many, Many years ago, a fellow showed up with a turbo Fiat X19, running a 32/36 and he ran it with NO FUEL JET in the secondary!

We did bore out the secondary, enough meat to take a good cut, then do a back cut to regain a "venturi" effect. That really increased the air flow.

Make sure you are using the right top gasket of course. Picture attached of the 2 available. For what it is worth I put the bearing kit in also, makes the carb very smooth in actuation.

Make sure, if you can with your compressor bypass valve, that it does NOT pull open till at least 16" or more of vacuum, as that keeps the boost up when shifting as much as possible.

Float change for sure.

I had a 1982 SR5 with the 3TC motor, I loved it as that was a torquey motor!

Not much else I can add at this point...keep us posted on progress.
Ok thanks Keith..

Only thing is that i just ordered two of those 3.00MM needle and seats!! Well we will see how it goes given the HP goals i am chasing..

Yes i do have a wideband A/F ratio.

I did buy the bearing kits for the throttle as well but i figure i will try out the carbs with the standard shaft seals as they are new without play...

I am not sure on where exactly you are referring to with this :

"We did bore out the secondary, enough meat to take a good cut, then do a back cut to regain a "venturi" effect. That really increased the air flow."

Can you elaborate a bit? Thanks
stanis82
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Joined: 23 May 2018 07:02

Re: Turbo weber 32/36 questions(blow through)

Post by stanis82 »

stanis82 wrote: 17 Jun 2020 09:39
bertvorgon wrote: 16 Jun 2020 09:51 Hey Teran, welcome back!

Wow, time has flown since this post started. You are on the right path for sure, don't know if I can help much as you are on a path the is a new frontier, blowing through 2 carbs in a drag application.

First thing for sure is make sure fuel delivery lines can deliver the VOLUME required. As mentioned, at one point I had that 3.0 MM needle and seat, which I ultimately did not need and went to a 2.5 MM needle. It turned out that was my learning curve to have enough VOLUME of fuel.

I too milled the top choke plate area down, to increase air flow in my air box. You can see in the picture the amount taken off.

Only testing will tell if sealing off the secondary air is a good idea or not. Do you have a wide band to monitor the A/F ratio? I know at one point my main fuel secondary jet was just over 3.MM. Many, Many years ago, a fellow showed up with a turbo Fiat X19, running a 32/36 and he ran it with NO FUEL JET in the secondary!

We did bore out the secondary, enough meat to take a good cut, then do a back cut to regain a "venturi" effect. That really increased the air flow.

Make sure you are using the right top gasket of course. Picture attached of the 2 available. For what it is worth I put the bearing kit in also, makes the carb very smooth in actuation.

Make sure, if you can with your compressor bypass valve, that it does NOT pull open till at least 16" or more of vacuum, as that keeps the boost up when shifting as much as possible.

Float change for sure.

I had a 1982 SR5 with the 3TC motor, I loved it as that was a torquey motor!

Not much else I can add at this point...keep us posted on progress.
Ok thanks Keith..

Only thing is that i just ordered two of those 3.00MM needle and seats!! Well we will see how it goes given the HP goals i am chasing..

Yes i do have a wideband A/F ratio.

I did buy the bearing kits for the throttle as well but i figure i will try out the carbs with the standard shaft seals as they are new without play...

I am not sure on where exactly you are referring to with this :

"We did bore out the secondary, enough meat to take a good cut, then do a back cut to regain a "venturi" effect. That really increased the air flow."

Can you elaborate a bit? Thanks
Here are pics of the twin manifold

Image
Image
Image

Keith do you think i should remove that pipe that connects the two carbs on the manifold? Wondering if it will affect boost flow into the engine
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bertvorgon
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Re: Turbo weber 32/36 questions(blow through)

Post by bertvorgon »

Not sure what to say about the balance pipe, I would maybe leave it in as first test. Boost overcomes a lot of flow variability.

What I meant about the secondary is that we milled the secondary bore to a larger diameter, at the venturi point, then, we did a backcut under what is now a very minimal venturi, to give MORE of the venturi effect.

So, we basically made the 32/36 which is the throttle plate size, the actual venturi size is 26/27 MM, so we made the secondary about 34 MM+, really increasing airflow when the secondary is open.

I wish I could remember how much of a cut we did, it is so long ago and I never wrote it down in my log book. Too hard to measure now with the carb in place and booster venturi blocking a measuring tool.

That mod, coupled with my larger cam at the time, really let my engine breath past 6,000-6,500 RPM and 8,000 RPM was easily achieved in 5th gear.

Possibly in this attached picture you can see how much bigger the secondary venturi is, almost same size as throttle.

Another trick for flow is you can mill the throttle shafts a bit flat. All these type of tricks really do increase flow.
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Bored secondary
Bored secondary
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"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer
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bertvorgon
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Re: Turbo weber 32/36 questions(blow through)

Post by bertvorgon »

I just did some reading/research on motor sport in Trinida/Tobago...WOW...I am amazed at what goes on there, I had no idea.

Nice to see your Government was onside for motor sport too, we had ZIP support here many years ago when looking for a new road race site. We ended up, through the good graces of the drag strip owner, getting a small road course incorporated into the drag facility.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer
stanis82
Posts: 15
Joined: 23 May 2018 07:02

Re: Turbo weber 32/36 questions(blow through)

Post by stanis82 »

Lol.. Yep we love motorsport down here!!

Well just an update... I haven't gotten to run my double 32/36 weber setup as yet and i haven't even gotten my turbo connected to my single 32/36 even!!
Got some sorting out to do with the car first in other areas...
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