Intake runner diameter

[amichie]

I have found a couple of different sources that suggest the intake runners on my 7m-ge engine should be about 36mm to have a peak torque in a useable rev range.

The book "Four stroke performance tuning" which seems to be very good reference fo NA stuff suggests that the intake runners should be about 1.1 to 1.2 times the intake valve diameter for a sports non race set up in a four valve engine.

It also suggests that intake runners should be up to 1.3 times for a race application.

Given that a stock 7m has 32 mm intake valves this gives a target intake runner diameter of approx 35 to 38mm.

For the race application I would need approx 41mm intake runners.

So why did toyota make the over 43mm in diameter at their smallest point, is it to moderate the torque to make it more granny friendly??

This online calculator suggest my torque will peak at approx 6500rpm which is way too high to be useful.

http://www.wallaceracing.com/runnertorquecalc.php

The intake runners seem to be a little short also.\

Has anyone tried reducing the intake runner size on Toyota engines? I think it is common on old V8 engines

Anyway, I am considering making up some venturi style inserts for the intake manifold to see what effect it has.

[Duk]

I had a quick play with that 'calculator', and I think it should be used as a guide only. It doesn't ask for enough info. and assumes too much.

David Vizard wrote some good stuff back in the (his) day. Typically aimed at pushrod yank iron, the logic still seems aplicable to most engines.

http://www.autospeed.com/cms/A_107771/article.html has some good Vizard quoting formula.

[oldcorollas]

poor port design may reduce effective port diameter, but the losses at the surfaces and corners...

the race thingy probably assumes the ports are a straight shot with ITB.

[amichie]

Anybody got measurements of a 2jz-ge intake ports and runner dimension.

In the images I have seen online they seem to be more of a small port style than the ridiculous large prots used on the 7m.

See this example.

http://users.tpg.com.au/users/loats/...adporting.html

[abently]

What are you trying to achieve exactly ?

You have to understand that the 7M-GE Engine (and all those Toyota Engines) around that time were already highly developed. The only later improvements which increased power/torque was more vertical intake ports and VVT-L/VVTi-L. The intake system is designed optimally to the Cylinder Head intake ports. If you change one, you need to change the other to see any possible benefits.

Not being negative, but you would actually see a better "butt dyno" improvement in improving the Airbox intake system (refer the the many Autospeed articles). If you wanted to spend $2K on the Engine, assuming its in excellent health, I would recommend you get Cams or bolt on a Factory Turbo setup.

If you wanted to try something "trick" you could buy/fit a proper High Flow Ceramic Metallic 4" cat & mess about with its distance from the Headers outlet to create similar Expansion chamber benefits, but that is something you would only do after all the N/A Engine mods.

[amichie]

What are you trying to achieve exactly ?

If you read my original post all will be revealed.

My main question is why did they make the intake runners and ports so big?

I suspect that the 7M head was designed as a huge compromise between its intended use as an NA engine, a turbo engine and possibly some plans Toyota may have had to use TVIS style intakes.(like that used on the 4age not the ACIS they used on the Supras etc)

When the 7M was released Toyota made a big fuss about it having a very flat torque curve with less than 10 % variation in torque between 2000 and 6000 rpm. Maybe they did this by removing any inertia effects in the intake ports and runners.

BTW I spent the holiday Monday in the shed making some 36, and 38mm venturis for the intake runners. Will see how they go.

[abently]

My main question is why did they make the intake runners and ports so big?

I suspect that the 7M head was designed as a huge compromise between its intended use as an NA engine, a turbo engine and possibly some plans Toyota may have had to use TVIS style intakes.(like that used on the 4age not the ACIS they used on the Supras etc)

I disagree completely. If you look at the power output per litre and remember what the GE designation meant to Toyota. I'm happy to be proven wrong..

When the 7M was released Toyota made a big fuss about it having a very flat torque curve with less than 10 % variation in torque between 2000 and 6000 rpm. Maybe they did this by removing any inertia effects in the intake system

That I agree with.

I hope your going to log results on some repeatable instrument ahem dyno maybe..

[cambelt]

That flat torque curve was the ACIS version i recall . 2JZ-GE ports are still oval but smaller , like the switch from bigport to smallport 4AG .
Dave

[cambelt]

Also , 7M,s have many diff head numbers , with the main differences in the divider between the valve ports. Im in with any research on the
7M as they are still a great engine.
Dave

[madmont]

You would expect Toyota to get it right with all their resources.
On the 2JZGE and 1JZGE the runner length is "varied" by a valve in the plenum .
If you have a look at a Pajero 3.5 litre the intake runners have their lengths varied by a series of butterflys on a long shaft which directs the intake along a much longer path at lower revs. This feature may not be on all of them .

[amichie]

Did you take into account that the 7M has 2 intake valves per cylinder?

Yes. That is covered in the book mentioned above.

[oldcorollas]

I disagree completely. If you look at the power output per litre and remember what the GE designation meant to Toyota. I'm happy to be proven wrong..

well... you're wrong

torque per litre is a better measure of efficiency (volumetric efficiency) compared to power.
are you saying that many very efficient german motors are inefficient because they make power lower in the rev range?

according to crappy wiki, the 3L 7MGE had 250-265 Nm... form 3L... if it was very efficient it would have been 280-290 at least. nowadays, 300 should be a minimum. i would hardly say it is "highly developed". they may have been "highly developed" for their day, but now they are barely above US offerings.. and that is not a good indication.


G just meant a different valve angle arrangement, resulting in different ports and cam gear system. if you compare say.. F1 heads to toyota G heads, you can see valve angle has little to do with being "sporty" or not.

Not being negative, but you would actually see a better "butt dyno" improvement in improving the Airbox intake system (refer the the many Autospeed articles). If you wanted to spend $2K on the Engine, assuming its in excellent health, I would recommend you get Cams or bolt on a Factory Turbo setup.

If you wanted to try something "trick" you could buy/fit a proper High Flow Ceramic Metallic 4" cat & mess about with its distance from the Headers outlet to create similar Expansion chamber benefits, but that is something you would only do after all the N/A Engine mods.

i suspect this is just your naivety talking?
you don't understand th eimpotance of port velocity? and you think airbox will have greater improvements than getting a better port size? umm...
Cams.... ok... and then what should he do abotu port diameter and length? "factory turbo".. masking the problem...

High Flow Ceramic Metallic 4" cat....
you don7t know what you are talkign about. cats are either ceramix matrix or metallic matrix with a ceramic coating.
as i posted recently, the STOCK cat for a 2L ST20x celica is a METALLIC core 3.5" cat... that is the same size as many "aftermarket performance cats".. and the core materials i slikely made at the same factory.
expansion chamber is a 2 stroke phenomenon no?

seriously. read the original post, and try to answer the questions, rather than just handwaving on things you seem to know very few specifics on..
OR, be specific abotu the suggestions you make, instead of juts typing words with no meaning

[amichie]

you don't understand th eimpotance of port velocity? g

This is my main point of interest. The inertia effect that you get at high port velocity is, I think, not being exploited with these large intake ports.

[amichie]

I was at the machine shop this morning picking up some parts and he had a pair of nissan rb25 16 valve turbo heads on his CNC mill. They had ports that were a similar shape to the 2jz and looked even smaller again.

[madmont]

I measured a few heads I have here
Mitsubishi 4g92 16 valve has 30mm dia valves and 45x28 oval runners 400mm long
Mazda 2 litre v6 24 valves 30mm dia valves and 42x28 runners 330mm long
Toyota 1800cc 4S 16 valve head 30 dia valves and 44x34 ports