Intake Performance on a budget

[Lonewolf]

I recently got my vacuum meter working today and its fully built and ready to go. I'm going to use it to hopefully find ways of improving the intake system, and then modify the areas that need it, leaving the rest of the intake stock. I did a quick check of the vacuum gauge today to make sure it was working, and i glimpsed it at around 15 or 16 inches of water, just over 1/2 a psi of vacuum from the intake pickup to the hose just before the throttle body...

I'm going to do some definite readings tomorrow with a friend recording the gauge readings and letting me drive. From there i should be able to find the weak points in the intake and recover this 1/2 psi. The throttle body and beyond are not being modified at the current moment.

I know that most of us here are not millionaires (well not yet anyway) and so this is being done on the cheap, but not of the unreliable-blow-up-your-engine-after-5-minutes kind of cheap. Anyway a summary of things i'm expecting to modify/replace to reduce the vacuum:

- Intake Pickup
- Air Flow Meter
- Air Filter Box
- Ducting

As i'm doing this and posting afterwards you can choose to do if you want and with no guesswork. Other things i will be doing to the intake after the vacuum problem is solved include:

- Insulating the piping
- Installing my modified throttle body
- Insulating the Intake Manifold (the most expensive gasket ever and most expensive modification i'll likely be doing at the current moment.. cost me $60 for the gasket blank.)

Stay tuned theres more on the way

[huskyracer]

Sounds like some serious sientific investigation is going on here mate!!
I like your style! you say you have a 1/2 psi drop from the intake to the throttle body, if you can make that near zero i would have thought you would gain quite a bit of power, keep up the good work

[jtbo]

Carburettor airfilterbox is different, but there is huge restriction from cold/warm air intake flap. I did remove it and only thing it did was that car goes now with lighter throttle and there is more power when I floor it.

I have also removed vaporizer, or what it is called, that made bit more power too. Could be that I put vaporizer back when I install fuel injection, but let's see.

There won't be mass air meter in my fuel injection conversion so I think I can pretty much max airflow before throttle body.

There is little restriction from throttle body, but there is few things to do for it too. make edge of throttle plate sharp and make screws to be inside of axle as much as possible. In that place even small changes make difference.

I'm going to polish intake manifold from inside too. Cylinder head is then next winter job.

[Lonewolf]

Well i have a few days off this week and got inspired by one of the car modding articles that used some megabuck instrument to design a custom intake. I made a cheaper version of that instrument for what $10 and its just as accurate (can measure down to 0.0025psi if needed) in measuring both boost and vacuum. And when i'm done with the intake i'm going to see if i cant use it for some better cooling on the car for both radiator and brakes and maybe even some downforce, but i'm starting off with this little something simple first.

Took the Proper Vacuum readings today, put a bit more water in the gauge as a few air bubbles were the cause for the over 1/2 psi reading yesterday. The peak vacuum would be higher again at 6000rpm but the traffic was picking up so i called it a day on the 5500rpm run.

2000rpm - 5.5 inches
2500rpm - 6.5 inches
3000rpm - 7.5 inches
3500rpm - 8.0 inches
4000rpm - 9.0 inches
4500rpm - 9.2 inches
5000rpm - 9.5 inches
5500rpm - 9.7 inches

This is just over 1/3psi, which while not as high as before, still allows room for improvement, the rest of the data gathering is going to happen tomorrow when i get a multimeter and pressure switch as i will be able to measure intake temps and pressure zones across the front of the car and from there design an intake that makes power and maybe if i'm lucky a positive pressure (aka boost) at the intake pickup.

Just out of curiosity i'd like to guess a (3hp) increase if i can get the intake 4 degrees cooler and reduce the vacuum to 0, but i'm hoping i can get around 6hp from modifying the intake before the throttle body. I just thought i'd state the 3hp bit now so i can see later on if these magic formula's for predicting power gains are accurate

Also out of curiosity Jtbo, how do you plan on porting the insides of the intake manifold? I managed to port my spare throttle body, but am stumped with the manifold at the moment. Its the only thing left to before i can put the new throttle body, manifold and insulating gasket on.

[jtbo]

It is not easy to find tool that can polish inside of intake manifold as manifold has some curves. I have planned a tool for it, only problem is that it is difficult to translateas I have not used to explain it in engilsh

Steel wire is needed (is it called that?) then something soft like a sponge and of course sandpaper. Sand paper is glued to sponge that is made to proper shape and size so it can fit inside intake manifold runner. Then steel wire will be sticked through sponge bend to u-shape and again trough sponge and finally 90degree angle to wire so it will secure sponge and there it is. It is slow tool, I don't think that it could be used with drill, but so far only solution I have found.

I have not yet build one but time is closing in, I need to start make all those mechanical things now as my Megasquirt unit is ready.

[Lonewolf]

Ok, My meter now meausures boost as well as vacuum.
I noticed the pipe just before the airmeter was sucking air into it, so i unhooked it and left it to feed from the engine bay while i did another run, it seems to have knocked the vacuum down to under 5"(will confirm this after work later). I figure the pipe takes air from the intake to cool the exhaust for emissions reasons... If it can feed from another air source it will do its job and let the intake perform better. The Idle vacuum dropped from 1.5 inch down to 1 inch. i think also the majority of the remaining vacuum is in the air meter as i measured the vacuum before the meter and there was pretty much none, will check that later also. The pipe does also let some exhaust noise thup through it, loud enough to fail for a leaky exhaust pipe, but not loud enough to be unpleasant to drive with(for me anyway).