Hello everyone,
I have been reading and searching this site for quite a while, and this is my first post. I am hoping to tap the expertise and experience of the members here. To begin with the latest project is to add Twin 78mm Borg Warner turbos to a 565 big block Chevy in a C10 pickup. I added a list of all of the components that I currently have at the bottom of this post. my biggest concern is maintaining the street-ability of the combination. I am designing a top for an Edelbrock 70855 intake that will fit under the stock hood and incorporate two inter coolers, one on ether side of the manifold. this design would require two throttle bodies. If I keep the throttle bodies the same size as the output from the turbo that would mean two 90mm throttle bodies. So the big question is: will this make the low speed drive-ability impossible? Is there a trick to getting this to work? Something like the old tune ports had, a special cam on the throttle cable? The plan is to keep the boost low at around 15psi max.

565 BRC 4.25" crank, supposed to be Oliver rods (look like Howard rods), Wiseco 5103H100 pistons (15cc dome 10.75:1- can be milled flat to 9.2:1).
Brodix BB2 plus heads with 2.3" intakes and high temp exhaust valves added. 292.8/385.2 flow @0.700 lift.
Straub custom turbo solid roller cam .663/.689-256/256 at 0.050".
Edelbrock 70855 EFI manifold.
(2) S478 Borg Warner Turbos 1.32/96mm T6.
Stainless Works 2.25" 3.5" up and forward turbo headers.
(2) JGS500 50mm waste gates.
(2) JGS600 Blow-off valves.
FAST XFI fuel injection with traction control.
FAST distributor-less ignition.

 

This sounds like a sweet project, I would think with that many cubes, and enough stall for the cam you have you wont have too much trouble at low RPM. There are going to be some serious drivability issues with that much power on the street though, what chassis is this going in? Whats the reasoning for running two throttle bodies? It seems like lot of complexity for very little real gain.

If you have some time and curiosity browse the advanced tech section there is a long discourse on intake manifold design. Focus on the posts by Boost Engineer.

 

I would look into having one larger intercooler, dual inlet, single outlet, and a single throttle body. Much simpler to set up, and less parts to buy.

How do you plan on getting the power to the ground in a light pickup truck? The FAST traction control will be employed full time!

What is the HP target? Sounds like it could be well into the 4-digit range.

Al

 

Thanks for the replys guys! My biggest concern (aside from the obvious) is the opening of two large diameter throttle blades being an on off switch (to use the terms from elsewhere on this site). I have had good luck with using the progressive four barrel type throttle bodies, but have zero experience with the larger diameter single throttle bodies. I don't anticipate having no bottom end. I planned on bleeding off most of the pressure to keep from making too much torque at the bottom end. In it's previous life (in my Camaro) the engine made so much bottom end torque (520lb/ft @ 2300RPMs at the rear wheels) that it just smoked the tires up with anything more than quarter throttle. I changed the intake manifold for a single plane and the car got faster everywhere. Originally I was shooting for 1200HP. After I purchased the parts from Forced Inductions, during a later conversation, he mentioned that it would probably make a bit more. So I am not sure when or who talked me into the tunnel ram intake. It is surely just for looks and cool. I am planning on keeping the whole thing under the stock height hood. That only allows at the most 2.5" on top of the tunnel ram. To keep the volume low and the response up, I was going to put an inter-cooler and a throttle body on either side of the manifold. These would feed the manifold from both sides through the top. If the opinion is that i can not make the two throttle bodies work well for street driving I will have to change my plans.
Ben, I have been following the discussion about intakes. I will need to go back and re-read the whole thing. I an not really worried about optimizing my setup as it is way too much power already. you are absolutely correct about everything. In my defense, I have been told that 800HP is unusable on the street and I really enjoyed it!! The main reason for the Turbo's is to revive the drive-ability. The cam that I was running to make that kind of power is not parts friendly, and between the surging and tuning at low RPMs, are not fun to drive.
Al, as stated above they are just for cool. If I have to ditch the plan I will not be too broken hearted. realistically if the motor made 750HP NA with 15 lbs and inter-coolers it might make 1500HP.
Thanks again!!
Joe

 

Twin 90mm's is a lot of tb, but many are running a single 90 on close to half of your cid, and hp, so I don't think it's too much of a stretch.

 

Is this one of those Australian cars for a burnout competition?
I wonder how many cement bags it'll take for traction. Might even need a tank back there ! lol.

 

Thank you for your input Mnlx. That is the kind of input I was looking for!
724QuikFast, lol, no that is not the usage. I had a Ford Ranger with a 427 Windsor in it, and I always felt that it was just waiting to kill me with any small mistake. This one will probably be worse! I am hoping the traction control will help tame it down a little, but I am not confident that it will help at low speeds. The traction control works off the drive shaft and measures the rate of acceleration to detect tire spin. With the engine NA in the Camaro it had a tendency for the wheels to do a slow spin on wet pavement when cornering. This caused the rear end to swing out. I have a 35 gallon fuel cell that is going in the back, but that might just make things worse for anything other than strait line.
Joe

 

Why FAST .

haven't heard to many running it as of late .

 

I bought it back when It was the cutting edge...

 

You mentioned that you have used progressive throttle bodies before. Why not stay with those?
I am toying with a similar deal with a tunnel ram. Either I will get a snorkel top made for it or use two throttle bodies. Some say that the two throttle bodies are an invitation to leaning out either front or back if each turbo isn't equal. But there is a plenum under the throttle bodies which could help equalize pressure.

 

yeah twin 90's are overkill. i built my 383 sbf motor years ago with a 75mm tb i already had and used it since it was the same id of the 3" piping i was using. fast forward a few years with a bigger engine turbo etc. i know there is a pretty decent pressure drop from turbo to intake but it ended up still making enough power to get a 3300# car to mid 8's

 

Thanks guys.
Bucky, the progressive throttle bodies that I am referring to are the four hole type like carbs. they don't really work for the front facing intake openings. The front openings will feed a tapered end cap that feeds the inter-cooler cores. the cores are currently planned as garret 1000 hp cores. the air will be 90 degrees through the inter-coolers. and then over the top of the manifold from both sides eliminating the distribution issued of a single front throttle body, and keeping the manifold height above the lower intake to less than 3". It will fit under my hood. The intake is almost 17" long at the smallest. I am sure that it is not that simple with the air flow. I was planning some sort of half-pipe down the middle of the top of the upper to direct the air downward toward the runners. I have been re-reading the posts that Ben had recommended in the advanced tech section. When I get the CAD models more complete, I will be hitting up Boost engineer (Tom Vaught)for input.
Ashford, I know it is overkill. It is one of the trade-offs that I made to fit everything under the hood of my truck. I could neck the tubing down to use 75mm throttle bodies. lol, It really goes against my nature. It will still make way more power than I was originally shooting for. My experience with the engine with a 2000CFM progressive throttle body was that it only took the pressure of the weight of my foot to drive around a "normal" traffic speeds. It was easy to do, and I am concerned about maintaining that level of ease of driving. I really plan on driving this thing every day during the good months up here in the north.
Joe

 

A single 90mm throttle body can consume enough compressed air on a big block to put 3000lbs in the bottom 4s in the 1/8. I would go with something in the 75mm range personally, if you are dead set on twin throttle bodies.

 

Thanks for your input. I am definitely changing my plans to 75mm. I don't want a truck that isn't fun to drive. I don't believe that it will, but I would give up some horsepower for drive-ability. The power level has spiraled out of control. I figured I could get away with my 4L85E that was built for 900hp, but that is just a dream now. I would have loved to put a six speed in this, but the cost of the "good" transmission is almost ten grand, and and I am afraid that the torque of the turbo engine would make short work of it. I appreciate everyones input. I will be asking a lot more questions!!
Joe

 

These guys would disagree with you. Two heavyweights beating on stock Tremec Magnum 6 speeds on sticky tires. If they're not breaking them...

 

Thanks for the reply! That is an awesome video! It inspired me to do some digging and I found This:

http://www.superchevy.com/features/1404-1986-pontiac-trans-am-3rd-gens-a-charm/#photo-05.

A 86 Trans Am with a 540 big block making 1407HP and running a ZF six speed. They are running a Pro-charger, but I don't see that being an issue. The intake design and layout are Identical to what I was thinking. They used two 75mm throttle bodies. Funny enough part of the title to the article is "Sanity Check". Pretty much where I was headed, just with a poorly balanced brick. I mean Truck. I have a few ZF transmissions sitting around the garage. I would need to send them to a specialist (ZFDoc) to build them up, but I think modifying two transmissions would probably cost the same as the Transzilla trans and leave me with a spare. I have been running a SPEC supper twin clutch in my Camaro for a while. They also make a super twin clutch for 1500HP. It looks like I can move the engine and trans back (and down) about 5 inches and still have the shifter in a comfortable position.
I appreciate all of the comments and input!!
Joe