Intake manifold modifications

[Anonymous]

Part of my ultimate 1zz build is the inlet manifold which I am working on just now.

I thought that I'd post some info that maybe useful to some of you...

Remove the inlet manifold & you will find that the inlet manifold runners are quite a bit undersized compared to the head ports - around 3mm.

You might think that this is to allow installation tolerances...but no. The inlet manifold has a good fit on the studs.

So, first thing to do is grab your Dremel and open up the bores a bit. Beware that the gasket seal pocket is close to the bore so go easy. The material comes off really fast. I took it down to approx 1mm thickness to the gasket groove, then blended it smoothly into the runner for around 20mm in.

http://www.box.net/shared/4vn4zrpog4
http://www.box.net/shared/5wfb3q94o0

Next, stick your finger into the throttle body opening of the manifold. You will find that there is a huge sharp edge lip round the edge of the bore nearest the runners. You will also feel a nice radiused edge if you feel in a bit more. Looks like manufacturing ease took priority over performance.

http://www.box.net/shared/9e7xy40kc4

Grab the dremel again and blend into the radiused area. This takes a bit of material removal but is worth it.

Clean it up and you are done. I don't have numbers for this mod, because my engine is in a million bits at the moment. But rest assured, you will get some gains for sure.

[custardavenger]

Sounds good

Can I interest you in a 60mm throttle body?
 m http://www.mr2roc.org/phpBB2/viewtopic.php?t=20473 m

[kanujunkie]

i've got to look into this as well, going to get a custom intake built rather than the fragile stock plastic one, just need to find the time  s:roll: :roll: s:roll:

[Tem]

Have you thought about using the 2ZZ manifold...? The more I look at it, the nicer it looks.  s8) s8)

[Anonymous]

The stock manifold has runners basically the same area as the port in the head - a fraction less actually (as I say in my previous, it is a few mm less all around). Even then, the smallest area in the whole inlet tract is the valve throat area, so putting on a bigger inlet manifold will only hurt bottom end torque and do little for top end power.

As for a bored out throttle body...I am not sure - in my exp the loss of torque low down will probably be a bad trade off for top end power. I prefer to stick with smaller cross-sections with smoother profiles so I am going to be dremel'ing out the body...knife edge butterfly, glue it in, reduce the screw protrusion to the air flow (use permanent stud-lock to prevent engine death due to bits coming loose)

Mostly my concern for smaller port areas is because I am fitting stage 2 crowers on....scavenging might be an issue though and this may indeed be helped by the throttle body enlargement.

[Anonymous]

Custom intake?

Have you seen the shape of the ports in the head? the fabrication will be a very expensive job. Also, the space constraints around the manifold mean that you will end up basically with what you have already except in 316 or 304 SS. It will end up far heavier than the plastic one as well.

My opinion, save the money for better things. Get the dremel out.

btw, the manifold is fibre reinforced plastic. tough stuff. what are you expecting to do to it that gives rise to concern about its strength?

[Anonymous]

About 15psi I think. Stu's got a C2 turbo kit on his car.

[aaronjb]

ISTR it's been fine to 30+psi for people in the states (like MWR) - but Stu is convinced his is going to explode  s;) s;)

[Anonymous]

You've heard Stu's car though, so I reckon he might just be right  s;) s;)

[Anonymous]

15psi works out at around 140kg acting to 'blow' the manifold off the head. Compared to the preload in the bolting holding it on, this is negligible....

Plastic also does a good job of keeping the charge cool from the heat of the engine bay...

[kanujunkie]

There have been cases of the plastic manifolds disintegrateing and plastic dropping on the valves. Thor racing recommend that the manifold is replaced if your going to go higher than 10psi!!!

[Anonymous]

It is probably down to a high charge temperature softening the plastic and that causing it to fail in combination with the pressure.

I am N/A so no worries there.

[kanujunkie]

probably although i'm running a chargecooler and the intake temps are pretty damn low. Think the main problem is the thin seperators inside the intake manifold that can fracture

[enid_b]

for the inexperienced (not myself of course) but what are the projected gains and losses from doing this?

E  s:D s:D

[kanujunkie]

more than likely none, the intake is slightly tuned for the engine and remember that the maf is pre all of this and if you muck about with it too much then the fuelling will be out. Open the box and area's out too much and you'll only effect the streamlining of the airflow and accumulation buildup within the airbox section of the intake. If the airbox accumulation is increased too much then you'll end up creating a lag from the MAF sensor and the fuelling input which could create further issues. IMHO this is only worth doing on a tuned turbo application where a complete custom intake is made

[enid_b]

more than likely none, the intake is slightly tuned for the engine and remember that the maf is pre all of this and if you muck about with it too much then the fuelling will be out. Open the box and area's out too much and you'll only effect the streamlining of the airflow and accumulation buildup within the airbox section of the intake. If the airbox accumulation is increased too much then you'll end up creating a lag from the MAF sensor and the fuelling input which could create further issues. IMHO this is only worth doing on a tuned turbo application where a complete custom intake is made

stu, you lost me at 'none' lol

[Anonymous]

How can you comment on the gains when you have not seen the shape pre & post material removal? Have you examined the manifold & head in detail (valves out, manifold off)

I am very doubtful that tuning will be required for small changes like this. You will be talking perhaps 1 - 2% improvement in flow. On turbo applications a lower improvement.

Talk of some kind of lag is highly questionable when there is no significant volume change in the manifold. Inlet charge does not 'build up' in the plenum with N/A applications, what you are alluding to is resonance in the inlet tract 'driving' more air into the engine, and this being messed up by these changes. Well like I say, minimal volume change and no length change means this is largely unchanged.

[Tem]

There have been cases of the plastic manifolds disintegrateing

Weren't they all related to the buggy e-Manage, which sometimes ignited fuel in the intake when you turned the ignition on?

I don't recall anyone having an issue with the plastic manifold other than that and some do run them with crazy pressures.

Thor racing recommend that the manifold is replaced if your going to go higher than 10psi!!!

Then again, TTE said that you can't boost above 10 psi anyway, cause the block will twist.  s;) s;)

[kanujunkie]

How can you comment on the gains when you have not seen the shape pre & post material removal? Have you examined the manifold & head in detail (valves out, manifold off)

thanks but i'm not exactly a newbie round here and yes i have seen and studied a stripped down block(Mark has one in his garage at the mo)and i'm neither a numptie to engineering being a licenced engineer. I just think your logic on this is misplaced, the stock manifold in NA format has some tuneing from Toyota but this is mainly in the air box attached to the inlet tract that hangs under the scrolls. Personally i'd be looking at the volumes of air that the engine requires at full chat and comparing that with the volume flow that can be moved through the inlet, doubt that theres  much difference and creating a laminar flow into a vehicle engine is a good thing but with all the other twists and turns and parts like the belows just before the TB and of course the TB butterfly valve what you propose is not going to even make your 1% difference imho

[Anonymous]

so taking this further, do you think there is any point in optimising the port in the head? using your logic there it seems like you are saying that there is no point as it has been 'tuned' by toyota...

every engine I have ever worked on benefitted from simple porting in the inlet manifold. pick up and read dave vizards books on tuning the pinto & tuning the a-series engine.

Quoting..."the stock manifold in NA format has some tuneing from Toyota but this is mainly in the air box attached to the inlet tract that hangs under the scrolls."

Yes. That is called a plenum. You have just repeated what I said about where the tuning occurs. I notice you have not addressed your point about my modifications messing this up?

It is not about laminar flow. The turbulence creates a resistance to flow - that is what we strive to eliminate.

btw. what is a licenced engineer? do you mean chartered?

[kanujunkie]

btw. what is a licenced engineer? do you mean chartered?

no i'm a licenced CAA aircraft engineer

i see what your getting at i really do, but the application of it on the design and layout on the 2 is not going to gain anything imho, yes it would on a performance engine where everything is designed to create the perfect flow but on an engine like ours i just really dont think your going to get what you think your going to get. Prove me wrong and get it dyno'd

[Anonymous]

Ahhh. yes I just realised you had a profile to look at...! Avionics...

If you happen to have the manifold off then this is a free modification to perform with no downside. Just 30min work to do.

Obviously not worth doing on its own if you don't have the engine out.

I would take you up on the dyno test but it will be totally unrepresentative - my engine is being sleeved & bored to 1.93L right now, fully flowed head, 11:1 comp, stage 2 cams etc so have no base line comparison.

[kanujunkie]

Ahhh. yes I just realised you had a profile to look at...! Avionics...

i'll amend that then as it should include that i'm just completeing my mechanical licence at the moment making me multi trade

impressive list of parts there though, are you useing the MWR sleeve kit or another manufactuerer?

[Anonymous]

Yep, MWR big bore kit. So far $2500 spent. Worked out at around £1500 with all tax, shipping & delivery paid.

Hardest part was finding a engine shop who were capable of doing the sleeve installation & boring. Sleeve install, bore, block skim, head skim & line hone is around £400 (tbc, not picked the stuff up from the engine shop yet).

I am getting them to build the bottom end up for me. They are trying to source Crower lightweight series rods for me and are going to supply ARP studs and their standard race grade bearings.

[Anonymous]

Ah! the good old 'A' series days: 100 thou off the head, 731 cam, twin 1.5 SU carbs (or single DSOE Webber). So much more sophisticated than just ramming more mixture into the engine   s:lol: :lol: s:lol: