[Darren 639]

Rick Well I didn't want to post my et. Only because of the horrible time slips produced due to very heavy car and no traction the Gto only went 11.00 it would twist car so bad I had to put the radiator back in place every time. But it would instantly burn the tire when I wacked 2nd gear. And continue till 3rd where it would make traction and gain mph. Some have said car Shuld have run low 10s. The 62 is also way off on mt et. 9.03 real bad 60 foot times 1.40s. just wish I had chassy guy help me tune frame may have run low 8s. Did you have your header plates cut I would need to buy a set.if so where did you get them? thankfully I have some tig time under my belt and can build them myself. You are welcome to use my shop and we could weld a set up for yourself. But I am way over here on the R.H. side of the country. I run inline long shifter with faceplate gears. And it drives just fine on street. I built in reverse lockout for one time I shifted to slow on a Sunday drive to Cruze and it went into reverse. Wish I could post pic but I have iPad iPhone and the site won't allow to download attachments.

[RAMAIR RICK]

Darren, Don Johnston sells very accurate size and high quality EXHAUST gaskets as well as Intake gaskets for his DCI Ram Air V heads. When I talked to the guy who will be making my headers, he said we could use Don's high quality and correct size exhaust gasket for the template to start making the header flange. I hope that helps.
This will be an exciting year for many DCI Ram Air V headed engines and their owners.

[dci]

I sell header flanges as well in mild steel for my RA5's. I don't have any in stainless, but Like Rick stated. You can use my exhaust header gaskets for a template.

[Darren 639]

Ok Don I have a laser cutting shop in my area I'll need about 3 pairs and same for your intake. I'll have a set made.Rick let me know if you need a pair I'm sure 4 will be easy to punch out and if you do how thick to cut them out of. Don let me know if you need my address. And if I need to send you a deposit
To secure your loaner cylinder head

[dci]

Darren, don't worry about a deposit on the loaner head. As soon as I get it back I will send it to you.

[dci]

Working on a sheet metal tunnel ram design for my DCI RA5 heads. This is super imposed over my cast intake for a visual comparison. Plenum looks big to me, but that can always be trimmed down.

[Tom Vaught]

Say you are designing the intake/engine for the 500 cid guys. NATURALLY ASPIRATED.

How about some rough dimensions of the shape of your plenum in your design.

Tom V.

[LMSRACER]

Originally Posted by dci

Working on a sheet metal tunnel ram design for my DCI RA5 heads. This is super imposed over my cast intake for a visual comparison. Plenum looks big to me, but that can always be trimmed down.

As You already know, the Plenum Dimensions are Very Application Specific.

Although, I do Agree it does look a little big. A Little Too Long and a Little Too Tall.

If You were to Offer a Cast Aluminum "Tunnel Ram" Intake, You Could Design the Plenum Shallower. Then You Could Always Offer CNC Machined Delrin (Or a Similar Composite) Spacers in Various Thicknesses. That Would give the Added Benefit of Acting as a Heat Insulator/Isolator for the Carburetors or TBI Units.

Looks Great, Just My $0.02......

Larry S.

[Tom Vaught]

Larry, you guys still use the 70% - 80% of engine volume with carbs?

Tom V.

[dci]

We are still in the design stages and have not nailed down an exact plenum size yet. My goal at first is to see what it looked like and to have a plenum that is 540 cubic inches. After seeing how big that is that is not the way I'm going to make it. Like Larry stated, I think I'm going to make it smaller and if someone needs more volume they can build a spacer or top that will increase it. I'm thinking around 400 cubic inches will be a good starting point.

[Tom Vaught]

A 505 Pontiac with a 400 cubic inch plenum would be a 79% manifold.

A 535 Pontiac with a 400 cubic inch plenum would be a 75% manifold.

So you would be right in the Typical Design Spec range for a carbureted engine.

Tom V.

[dci]

I think runner diameter, taper, and length are way more important than plenum size at least for a drag race deal. I also think we need enough plenum volume so the engine can recover at max rpm too. Carburetor throttle bore and venturi size also has allot to do with recovery. These are the kinds of things I was trying to get people to discuss in my 2.3 HP thread. So many of the guy's racing don't understand the physic's and dynamics of a combustion engine. I just thought it would be of help if they started asking questions and offering idea's. Even if they are wrong. I always tell my son and the guy's working for me. Before you can fix it, you need to know how it works. Thanks for everyone's input and please continue.

[LMSRACER]

Originally Posted by dci

I think runner diameter, taper, and length are way more important than plenum size at least for a drag race deal. I also think we need enough plenum volume so the engine can recover at max rpm too. Carburetor throttle bore and venturi size also has allot to do with recovery. These are the kinds of things I was trying to get people to discuss in my 2.3 HP thread. So many of the guy's racing don't understand the physic's and dynamics of a combustion engine. I just thought it would be of help if they started asking questions and offering idea's. Even if they are wrong. I always tell my son and the guy's working for me. Before you can fix it, you need to know how it works. Thanks for everyone's input and please continue.

^^^ X2 ^^^

Intake Manifolds are such an Intricate/Important Part of the Equation. They're so Application Specific.

In Your Situation, without making 10 Different Intake Manifolds, You have to Offer Something that Errs on the Small Side for the Lower RPM, Smaller Displacement Engines and with Enough Material to Grow into an Intake with Large Enough Passages for the High RPM, Large Displacement Engines.
What would be Ultra-Trick would be an Intake Manifold with Adjustable Runner Lengths and Adjustable Plenum Volumes.

I think that most People don't realize just how well a Tunnel Ram Intake with the Correct Dimensions can Perform on a Street Car. Of Course, with Adequate Hood Clearance.

My $0.02....

Carry On,
Larry S.

[tom s]

Larry you are so right.I have been driving a repop factory bathtub tunnel ram on the street for close to 20 years now.Tom

[Tom Vaught]

A Guy at work built a super nice high rpm SB Chebby Custom TR engine with large taper runners. The engine did not make that great of power at the high rpm.

He had made some tapered inserts that reduced the taper from the head to the port entrance and the engine came alive. So Taper of the runner IS important with a carbed intake.

Tom V.

[moparcolt]

I love tunnel rams and have had great luck with them on the street.
I put on on this 64 Sport Fury, and it was awesome!
I had always read how tunnel rams were no good on the street, and hard to tune. I found that not to be the case.
I do think closing the right one and sizing the carbs appropriately is very important. But I think when doNE right they are just fine for street use.

I just recently used one in a 65 impala as well with good success

[Jim Robertson]

Don your cad design looks like the right direction for the engines we work with here as well as the 400 ci plenum. Offering Delrin or similar material spacers for additional volume/vibration/heat isolation is a very good idea.

For what it is worth/comparison: My junk (468 cid, iron D ports) has a plenum volume of 225 ci yes 225ci and that supports well over 850 hp on good fuel and runs 143 mph (7200 rpm) thru the mufflers at 3285lbs. Not big enough and probably why it runs so slow but it does have very civil street manners on the road and in traffic. :-)

I agree on the runner design offered above...get that right and save the customer a lot of time and money. Smaller plenum casting with optional spacers (1" and 2" thicknesses as an example) can cover many engine combinations.

For the carb guys I highly recommend you place the runner entrances "under the carbs" and do not abbreviate the end runner entrances by shortening the plenum box. Allow the full radius entry into the runner entrance the entire 360 degrees circumference. From my rough estimations using your manifold here, I believe you can cast a good runner entrance (with room to grow) and still run a MSD distributor. Hard core guys will run a belt drive front distributor

With the 500 cfm heads we have here, a single four top designed right could open a whole other market for your heads...people are asking me how can we get that done.

Also FYI...The NHRA legal pro stock engines we have had in the shop have had plenum volumes as much as 550 ci (HRE intake 2007 vintage.)

Good stuff...keep going

[dci]

Originally Posted by Jim Robertson

Don your cad design looks like the right direction for the engines we work with here as well as the 400 ci plenum. Offering Delrin or similar material spacers for additional volume/vibration/heat isolation is a very good idea.

For what it is worth/comparison: My junk (468 cid, iron D ports) has a plenum volume of 225 ci yes 225ci and that supports well over 850 hp on good fuel and runs 143 mph (7200 rpm) thru the mufflers at 3285lbs. Not big enough and probably why it runs so slow but it does have very civil street manners on the road and in traffic. :-)

I agree on the runner design offered above...get that right and save the customer a lot of time and money. Smaller plenum casting with optional spacers (1" and 2" thicknesses as an example) can cover many engine combinations.

For the carb guys I highly recommend you place the runner entrances "under the carbs" and do not abbreviate the end runner entrances by shortening the plenum box. Allow the full radius entry into the runner entrance the entire 360 degrees circumference. From my rough estimations using your manifold here, I believe you can cast a good runner entrance (with room to grow) and still run a MSD distributor. Hard core guys will run a belt drive front distributor

With the 500 cfm heads we have here, a single four top designed right could open a whole other market for your heads...people are asking me how can we get that done.

Also FYI...The NHRA legal pro stock engines we have had in the shop have had plenum volumes as much as 550 ci (HRE intake 2007 vintage.)

Good stuff...keep going

Thanks Jim for your insight. Intake manifolds are one of the pieces of an engine that if you get right can make a big difference in your HP. That's why I struggled with the cast intake I made. I just couldn't bring myself make a mediocre intake just to fit under a stock hood. Ironically enough all the guy's that were hounding me to make it fit under the stock hood haven't bought any heads yet LOL. I'm glad though that it happened the way it did. I like having a challenge and conquering it. My cast intake is very versatile and works extremely well. These drawings here are actually going to be for a sheet metal intake not a casting. So it can be built with any size runner that is needed for any situation. The plenum is the easy part of the design, because I can make it smaller and as you suggested just ad spacers to it. Or you could fabricate a top to suit as well. My biggest concern is the runner alignment in the plenum area. I want the runner opening directly under the carburetor throats like you suggested. So the best way to get that right is build a cad model and put carbs on it in the model. Then I can see exactly what it will look like before I even cut the first piece of aluminum. Kind of like that carpenter saying. Measure twice, cut once !!!!

Jim are you hinting that you have some 500 cfm DCI RA5 heads there???

[Jim Robertson]

Oh ok I thought you were looking to cast a tunnel ram type intake for the racers that were not limited by hood clearance issues. My bad...
Sheet metal intakes are no problem to build but some class rules can complicate the use of same.
500+CFM DCI Vs are a reality on this bench...but they are a little way from making heat. At least we have not hit water. ��

[JSPONT]

Hood are over rated!!! LOL