Computer Engine Modelling, (18rg in particular)

[Steve M]

Ok, good to know, and I think pictures of heads that have been flow tested will definitely add value to the figures.

I hope to get my head tested when I finally finish butchering the thing.

[Mr DOHC]

imageshack's being a bitch, who can host pics

[SRacin]

Another cool thing to know for people doing things on the cheap is wat sort of differences using the early model cams would make...

[myne]

Interesting topic.

Has anyone ever fully flow tested the stock 4age heads?
I'd be curious what differences the bigport and the small port have in the real world.

[jeffro ra28]

Iv got the specs of all standard production cams for the 18rg. All i need is some accurate intake and exhaust system specs. I have found if you have one figure out of place the whole calculation goes out the window.

It will even calc injecter pulse length and spec etc if you enter the right feilds

I can model some 18rgs with stock standard cams. But it will not really be accurate if i cannot get ahold of some exhaust and inlet information. I do have the facilities to find out but not the time atm.

Plus im chasing CFM everyday at work and i dont want to be doing that in my spare time aswell:I:I


Oh btw, Running wade 137 cams, Phils flow table, 10.5 comp pistons, 2.2L, open headers and a crazy high flow intake it simulated an engine with 209BHP. Very impressive. It isnt quite accurate because of the open headers and an imaginary inlet system i wipped up tho.

[Steve M]

hmm, perhaps my goal of 200hp n/a might not be so out of reach.
Do you reckon valve size would make any difference? Probably not I reckon, as the valve is not usually the most restricted area of the port.

[Mr DOHC]

talk to RA_28, his old 18RG with 9.7:1, huge cams and 45mm webers hit 197hp

[jeffro ra28]

Steve, anything is possible mate.

If you intened to cut the valve seat out alot bigger valves would be needed. If your not cutting valve seats at all you would probly even get away with the using the smaller valves out of an 88210 in in ur 88270 head.
I have constantly got my eye out for some second hand titanium valves lying around the shop. The right diametre is usually easy to find but i will definantly have to shorten them. Yummy titanium!
I am surely hoping to atleast get 200hp at the flywheel with my RG.

[Steve M]

I think it is better to have a valve that seats farther out into the combustion chamber than farther in to the port, as a smaller valve would.
Having a smaller valve would mean less restriction at high lift, but more restriction at low lift due to its head being inside the line of the seat for more lift than a larger valve head.
I heared the other day that someone did a few tests and figured out that air/fuel micture doesn't like travelling around a (read "chamfer angle") corner of more than seven degrees. It gets turbulent around angles of more than this fugure.
Obviously we want a narrow but flat mating surface from the valve to the seat, but all the other angles on the seat and valve should be made less than seven degrees or rounded over.

[tricky]

Nice! I used EAP a while ago to model a couple of engines. I can't remember what output I got, and my copy has locked itself, but it definitely helps when tuning inlets and exhausts!! 200hp at the fly is also my target with 10.5:1 2.2L pistons, lotsa head work, probably TRD cams and quad throttles.

The unknown for me is how the quads will work out... They are the right diameter for good inlet tuning, and I should see gains with EFI over the DCOE45's...

[jeffro ra28]

tricky, if u hava specs for inlet, TRD cams and exhaust i can model an engine, i am actually trying to find this out for myself.

[tricky]

I don't have any data on the cams yet. AFAIK, Celica RA45 does though. He is convinced that the TRD cams are the best grind for the 18RG. There is a possibility that I'll haev TRD cams and pistons in the near future too...

[jeffro ra28]

There are a few different TRD profiles around, it would be handy to have the information on them.

[tricky]

Ooops! What I intend on using is the TRD rally grind cams. All I know is 304in/288ex. I think they are close to stock 10mm lift.

[Mr DOHC]

jeffro, look for SBC valves, they can be easily modded, thats what i have

steve, what u mean by "more restriction at low lift due to its head being inside the line of the seat for more lift than a larger valve head."