I am rebuilding my 3.0 litre inline-6 motor, it will be stroked to 3.23 l, turbo is 78 mm supporting 1000-1100 hp.
My manifold volume is 4.5 litre, should I increase it? AFAIK manifold volume has to be 1.5-1.8 times engine displacement.
I understand that smaller manifolds reduce turbo lag and hit harder, larger manifolds better for top end power.
Is my old manifold too small for stroked motor and 78 mm turbo?
Few pictures of manifold:
http://mk3ukr-supra.net/Intake manifold 01a.jpg
http://mk3ukr-supra.net/intake manifold 03a.jpg

Thanks

 

http://www.grapeaperacing.com/tech/inductionsystems.pdf

Grape Ape posted this a few months back along with this disclaimer:

Hope this helps.

 

In. Another good link for research on my sheet metal intake. Thanxx Ryan

 

In 1995, some people I was helping made their own Intake manifold based on some MANDY computer simulation work. The engine was a 406 cid Traditional Pontiac Engine with cast iron 240 cfm/runner heads. The engine made over 1600 hp and 1400+ lb/ft of torque on Methanol. It ran over 194 mph in the quarter mile in the very low 7 second range. Car weight was slightly under 3000#. The intake manifold volume was 1.5+ times the Engine displacement.

Some years later the Butlers and their Tuner "Travis" built a 482 cid engine using a manifold plenum made from a 6" diameter tube about 18" long.

http://butlerperformance.com/products/engines_assemblies/aluminum.html

Third picture down. The manifold volume was 1.055 times the engine displacement.

First test block dyno numbers: torque 2,105.2 ft-lb, and HP was 2,886.0 @ 7200 rpm
with a 4.250 bore and 4.250 stroke & 40+ lbs of boost (482 c.i.)

So you have an engine that made 6 hp per cid with a 1.055 times engine displacement
and an engine that made basically 4 hp per cid with a 1.5 times engine displacement
volume (with crappy heads). I would worry more about my next cup of coffee vs the volume vs displacement deal on a boosted engine. Much more important is even distribution to the cylinders. When you have to take away fuel from some cylinders and add it to other cylinders you know you have an air distribution problem in the intake.

JMO

Tom Vaught

 

Ryan, thanks for the link
Seems I will be fine without increasing volume of surge tank

Tom, thanks for above example. 2886.0 hp

 

can you elaborate any more on this Tom ? How poor can an EFI sheet metal intake distribution be ? Or how to pre-engineer to prevent said problem ?

 

Sometimes it can be simple things:

I was observing a dyno test on John Meany's old Dyno out (at his place) on an engine with a sheet metal intake for a BB Chevy. The engine was a boosted engine. The intake had two inlets across from each other (basically east/west on a north/south crankshaft). The inlets were in the middle of the engine.

We ran the engine and the engine had LOUSY distribution. All of the air was going to cylinders 3,4,5&6 (had to add fuel to those cylinders) and cylinders 1,2,7&8 were fuel rich.
Not enough air getting to them.

The intake had a deflector plate to keep the discharge air from one boosting device running into the air from the other boosting device on the opposite side of the intake.

The air would hit the deflector plate and go downward with most of the air going to the middle cylinders. John Meany removed the deflector plate and let the air from on discharge impact the air from the other discharge and the air distribution evened out in the whole intake. We could now ADD Fuel to the formerly "air lean" cylinders. Power picked up a bunch vs having to remove fuel to get the air/fuel distribution right for a given cylinder. By having even air distribution we could add the right amount of fuel to each cylinder and make more power.

Same deal happened on a "front fed" throttle body deal. The air was all going past the front runners/ cylinders and packing up around the rear 4 runners/ cylinders. Rear 2 cylinders needed a lot of fuel and on the front cylinders we had to take away a bunch of fuel.

We made a larger plenum intake with a "quick expansion" near the front of the intake to rapidly slow down the air velocity and the the power evened out on all of the cylinders. We "fine tuned" the distribution by trying different throttle body mounting angles (tipping the air) throttle body downward toward the front of the intake vs parallel to the centerline of the crankshaft centerline. We had air distribution with-in 1 percent on all cylinders with a intake that normally would have provided too much air to the rear of the intake.

This is the fine tuning that wins races. You don't give up any power, ever!

Tom Vaught

 

As usual Tom. So that explains intakes like this. http://img53.imageshack.us/img53/3500/70455514fh4.jpg
Sorry for the jacking to the OP. Hope it helps you. :-X

 

Exactly, they created the expansion near the front then played with the T/B angle to get the right distribution in their development process and then duplicated the manifold design on other similar intakes/ engines. Depending on the way the blade is mounted and how it swings you might need a T/B angle position that is different from my earlier explanation.
Some manifolds have the T/B cocked off to one side of the intake but still front mounted.

Your example is perfect for the theory though.


Tom Vaught

 

indeed

I love these discussions.

 

Since I am on "a roll" with the "story telling" I will add another story if the forum doesn't mind.

We were testing a Big Block Chevy with with Twin Vortech Race superchargers on a 2000 hp
dyno. Each supercharger had the ability to move over 1100 hp of air. 1 lb of air will make 10 horsepower typically. Every pound of air you move thru the engine will take about 1 hp so it takes 1 hp of energy from somewhere: (A supercharger belt driven by the engine or the turbine of a turbocharger driven by the exhaust) to make 10 hp boosted.

By rights we should have been making Steve Morris type HP back in 1996.

The guy had a custom made intercooler with 4 bricks: Air fed from each supercharger into the bottom of an inter-cooler plenum, through the first brick, then through the second brick, and finally to the engine. The same set-up was duplicated for the second supercharger. The intercooler was 4 bricks stuck together but each side was independent as far as air flow went.

The "Intercooler" assembly had the capacity to cool 2000+ hp as Steve Morris had a similar high flow large capacity inter-cooler at his dyno for the carb testing. Everyone knows his inter-cooler deal cooled down 2000 hp worth of hot air.

Back to the previous guy's testing.

The engine was way down in power. The charge temps to the engine were high and the efficiency of the coolers was far lower than the normal expected efficiency. They asked me to look at his set-up. This is what I found:

1) We put pressure gages on either side of the inter-coolers. The delta P across the bricks/ assembly was 5 psi boost loss. Each brick could pass only a certain amount of air. The bricks were in series for each side of the engine. Double cooling (which was good) but the individual bricks were acting like resistors in series. The old Mondo cooler from Vortech used 3 bricks side by side (parallel flow) and we know today that that set-up suffers with power loss at high hp levels. He only had 2/3s of that flow. We took the system off and the engine actually picked up in power.

2) I mentioned the "double-cooling" deal. This should have really lowered the charge temperatures (using ice) like Steve Morris shop does but the charge temps were very high. You can still make power with higher restriction IF the charge temps are very low.
On his set-up the owner had rigged up a little 5 gallon plastic bakery pail full of ice/ water
with 1/2" diameter hose to feed the inter-coolers. The water pump for this deal was one of those Bosch inter-cooler pumps designed for a single brick. I have tested those pumps and they will move about 6 gallons per minute. So here he had one little inter-cooler pump trying to feed 4 inter-cooler bricks. There was more bad news: He split the flow through a "tee" and then fed from the "tee" to the 2 lower bricks and then from those bricks to the 2 bricks closest to the engine and then finally back to the water pail through a shower head he had rigged up to spray the return water on the ice. water was barely coming out of the shower head.

He made 4 big mistakes, Here is what they were in order of importance:

1) The inter-cooler pump needed to be at least a 30 gallon per minute deal like the meziere
inter-cooler pump. Ideally he should have had either a single pump like the big 55 gallon per minute meziere remote pump or 2 of the 30 gallon pumps in parallel. No water flow = NO COOLING.

2) You ALWAYS put the coldest water into the brick water side closest to the intake manifold and then the heated water is routed back to the reservoir. A brick has two water nipples. The side where the air comes out of the 2 pass brick is where the coldest water goes in. He had his deal plumbed backward and was trying to feed 4 bricks with practically no water flow.

3) The pressure drop across the air side of a "water to air" inter-cooler brick should be about 1 psi. If you double the horsepower you add a second brick right beside the first brick in parallel so that the pressure drop remains at about 1 psi but you have double the cooling capacity. In the mondo cooler deal they added 3 bricks in parallel and for a while that deal worked great. Then the HP went higher and the air restriction (boost loss) got too high (according to some) as the inter-cooler efficiency dropped off at high hp. I personally think they needed a meziere 30 gallon per minute pump minimum if not the 50 gallon pump.

4) The size of his cooler lines was ok but the "Tee Fittings" were killing the flow. Guys today put the Water to Air inter-cooler in the back seat and run short lines from the water reservoir/pump to the inter-cooler. They make the air plumbing large and route it to the back seat intercooler as the heat picked up by the pipes is very low in the engine compartment as the boosted air is hotter than the engine compartment. Once the air is cooled by the inter-cooler it doesn't really have much time to pick up heat before it goes into the engine. Some guys who need to run the inter-cooler up front get rid of the pump and make a reservoir around the inter-cooler. This works good on a 6 second drag car. Not so good on a street car deal.

My point of all these words is you have to look at each part of the system and make sure it is right for the HP target. Otherwise you are scratching your head and asking "Where is the HP?"

Tom Vaught

 

Gonna start a new thread for our OP Tom. I got questions.

https://www.theturboforums.com/smf/index.php?topic=129510.0