Intake manifold (N42) cleaning and 60mm port matching questions

[Zetsaz]

I picked up a non-EGR N42 intake manifold recently and got a good chunk of the grease off but hoping to really clean it off and was hoping to get people's feedback on what's worked for them. The casting texture seems to hold on to some things.

 

Also, for those who have run 60mm throttle bodies; how have you gone about port matching to the new throttle body. I know BRAAP's guide says using the 60mm body is pointless without it, but others have also said you'll still have a restriction in the runners so don't bother. Most recently on a very old thread someone had a picture showing that you might not have enough material to just port it straight through and someone suggested just clearancing it so there's not a lip, which I guess just makes a bit of a funnel into the plenum.

 

Just curious what people have used for tools as well before I get into it. Here's as it sits with my new fuel rail and injectors test fitted. 

 

 

[seattlejester]

Mineral spirits worked pretty well. 

 

The trick I learned from some people who refinish transmissions and other parts is get it really clean, then take a torch to it to burn off the grease and other oil residue, then clean it with a volatile solvent (ethanol) that leaves no residue, then paint it silver. 

[Zetsaz]

Good info! Will have to try that tomorrow. Some of the hardware and the original heat shield are soaking in vinegar to get some of the surface rust off. Working incredibly well. Probably better for a separate thread, but I'm also thinking of what to do with that, high temp paint, or gold reflective tape or something. Need to look more into that as well. Will probably hold off on porting out for the 60mm throttle body for now. 

Edited April 24, 2018 by Zetsaz

[seattlejester]

Evapo rust works almost unbelievably well on hardware. I threw in a bucket of bolts I was planning on replacing just to try, I thought I dropped in some new bolts when I pulled them out from how clean they came out.

 

Gold tape thing seems to be popular. Ceramic paint works pretty well if you spend time to follow the directions.

[lowrider]

In previous manifolds that I have done I sand blast to remove the final layer of grim to get a consistent finish, then I powder coat them. Although if you don't have access to a sand blaster seattlejester's suggestion with the solvents and fire sounds like it would be the way to go.

 

The heat shield, I've high temp spray painted which holds up well for a few years. As far as the gold foil tape, I would be hesitant placing it on something that close to a possible 1500+F heat source. Depending on the manufacture, gold foil tape isn't rated to handle those types of temperatures.

I've actually been doing a bit of research on better insulating the intake manifold via beefing up the heat shield design, and I'm going to be placing a sheet of THIS on both the top and bottom of the stock heat shield when I tear it down in the next month or two. I've previously been running just the factory heat shield that is painted and I'm tired of the numerous heat soaking and vapor locking issues that I have been living with during the summer in the south. So, this year I'm taking a few measures to control under hood heat with the intake manifold heat shield being one of the areas of focus.

 

For porting for the TB, Ive always used carbide burr bits (like below) in an air grinder to smooth the transition between the throttle body diameter and the opening of the manifold.

 

I was able to dig up a picture of my current intake manifold in the process of being shaved and ported that shows the start of smoothing the inlet for a Weber TB. In the end, I removed the casting bumps that protrude down from the top of the opening as well. I hope this gives you some ideas.

 

 

[Chickenman]

I'll be doing this upgrade sometime in the future. Along with 100 other Projects I seem to keep putting off. 

 

With respect to BRAPP, the restriction in the runners is not as relevant to TB sizing  as people think. Importantly they are not looking at the complete operation of a Plenum manifold. Don't forget, ALL 6 runners have a combined flow that has to go through the Throttle Body. Any improvement on flow to ANY area of the Intake manifold will have an effect on the overall performance.  Especially to NA plenum manifolds. 

 

Adding a 60 mm TB and porting the TB opening won't give you much of a gain. But it is measurable. Removing the bumps at the TB intake definitely helps. 

 

Adding a larger Plenum while keeping the same size runners also results in a Performance gain. People who do not understand how this can work with smaller runners need to look at the design of Plenum manifolds . There are formula's for working out the Plenum volumes. I don't have them at my finger tips. But for maximum performance the Intake plenum volume has to be much larger than the Volume of all the Cylinders combined . 

 

The trick is reducing the Vacuum pressure drop  created inside the Manifold. Ideally you want the Plenum and TB to be large enough to allow the Plenum to be at atmospheric pressure at WOT . If you are creating a Vacuum in the Plenum at WOT, you are reducing flow to the engine. This is true on any engine. Most factory manifolds do create a Vacuum at WOT. 

 

Increasing Plenum volume and  TB size do improve performance. Even with much smaller intake runners. . All you have to do is look at V8 EFI Plenum racing manifolds. HUGE Plenums with HUGE TB's. TB"s have a much larger flow capability than a single runner. Or even all  of the cylinders together. It's all about reducing ANY restriction to flow through out the complete manifold, and also about keeping the Pressure drop minimised at WOT. 

 

 

 

[Chickenman]

I'll show you a picture of 4 Time SCCA National Runoff Champion Collin Jackson 240SX GT3 race car engine a bit later. Now these have to breath through a teeny tiny 38 mm restrictor on the engine to equalise HP. Andy Pearson, the engine builder at Specialty engineering can go Toe to Toe with any engine builder around.  

 

Colin is the only entrant in SCCA history to have won every single SCCA Runoff he has entered. This year the SCCA Runoffs are in Sonoma. Where Coilin holds the track record. Dare we  say 5 out of 5? 

 

This is a KS24 12 valve Datsun motor... breathing through a single 38 mm " Straw"..... and it produces 280 crank HP. For a " Truck " engine that isn't supposed to be able to Rev or produce much HP... this is astounding. 

 

There is s s**t load of work done to the Intake system and manifold. Including an absolutely  HUGE Intake plenum  Some very, very intelligent thinking going on here folks. 

 In the following photo... the 38mm restrictor is the black object just ahead of the Plenum. Look at the sizing of Plenums before and after the restrictor plate tube. You can't see the inlet of the restrictor tube, but it tapers smaller facing forward.   Bear in mind that the Plenum Volume also includes the large diameter silver tube attached to the rear of the Restrictor Tube. So the complete Plenum volume is rather large shall we say. Part of a successful restrictor Plate engine. 

 

Edited April 24, 2018 by Chickenman

[Chickenman]

BTW... that's the genius Mr Pearson himself making some final adjustments. You should see his Fab work. Thes cars are still State of the Art. And they were built in 1998 if memory serves me correct. Still the fastest cars in GT3 after 20 years.