Tom
Chats A Bit
Posts: 218 
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Post by Tom on Dec 9, 2016 15:14:17 GMT
Not to sound stupid, and also slightly off topic, but is there any gains to be had by going for a throttle body with a bigger internal diameter? Say off a litre bike or a 1300? Or to put it another way, is there a bhp or flow point where the size of the throttle body is the bottleneck or do they just flow air quicker? I am not informed about this what so ever as it is beyond my area of expertise, but I was assuming that at a given capicity there will be a certain amount of "suck" and for that quantity of "suck" there will be an optimum bore diameter to create the maximum flow of air. Something along those lines, it seems much clearer in my mind! |
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Post by Horney on Dec 9, 2016 17:19:26 GMT
This thread is relevant to my interests having bought a set of AE111 or something ITBs and a manifold for a 1.8 NB engine. Hoping to hav a built and running car by beginning of May.
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Tom
Chats A Bit
Posts: 218
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Post by Tom on Dec 9, 2016 18:29:48 GMT
This thread is relevant to my interests having bought a set of AE111 or something ITBs and a manifold for a 1.8 NB engine. Hoping to hav a built and running car by beginning of May. The OE toyota tbs? I am hoping to have the top end rebuilt early next year and be back on the roads  TBs arrived incredibly early this morning, made some adjustments to the trumpet side CAD files and now printing in the cheap stuff/at high speed for a test fit! Just need to sort out the rest of the stuff. There is a 1.6 inlet in the post to me so hopefully I can hack that up/mill it flush/make flanges next week and then get it all welded the following week ready to assemble over christmas! ....Sounds realistic   If anyone is interested in some experimental length trumpets I could potentially run a few off for people given the correct dimensions, for a few quid. No promises though! |
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Post by Horney on Dec 9, 2016 18:40:34 GMT
Yeah OE Toyota ones, I bought them off Vindi. Project thread incoming.
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Post by warpspeed on Oct 13, 2020 1:20:32 GMT
For ram tuning there is an optimum flow velocity where you achieve best cylinder filling.
If velocity is higher, there will be flow losses from pressure drop.
If velocity is lower, there is less flow inertia available to tune with.
That best cylinder filling point may be set to coincide with the power peak, or it may be set lower to give a wider usable torque band, depends on how peaky you want the engine to be.
Length has much less effect than having the right induction flow area and velocity.
Everything needs to work together.
Valve size, port size, and tuned runner, plus valve timing all need to be compatible and work best over the same rpm range.
Going crazy on just one thing will lose you power.
Flow velocity is also a function of cylinder displacement and rpm.
You can be sure that the original bike had this all worked out correctly, so you can probably scale off that.
Another less complicated guide to flow, will be horsepower per cylinder, which takes everything into account.
27-37 Hp per cylinder, recommended throttle body size 36mm
35-46Hp 40mm
43-56Hp 45mm
That should pretty much cover the range we are interested in.
Bikes go a lot bigger of course.
50-65Hp 48mm
60-77Hp 52mm
70-87Hp 56mm
80-98Hp 62mm
Reference for sizing "Four stroke performance tuning" by A. G. Bell, second edition page 139
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Post by dickie on Feb 12, 2021 18:54:02 GMT
I am just about to install a set of EV14 550cc injectors into my 169Bhp ITB eunos, currently on OEM Purples @ 62 psi.
I did not buy the injectors for the flow rate but the better spray pattern and control at the low end, The EV14s have a split spray pattern so they will hve to be aligned properly, I am hoping for better control at small throttle openings and faster pick up and maybe a bit more top end power, they should also be better when I do a forged engine build for high revs.
I will report back when I know more, the car is on SORN for the winter.
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Post by dickie on Feb 13, 2021 16:53:01 GMT
I have just finished fitting the EV14 550cc injectors and adjusted the Me 221 to suit.
The car started fine and has a smooth tickover. The only problem seems to be stalling after blipping the throttle so that will need some sorting out.
Its a bit cold in the garage at the moment, Even in Cornwall !
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TBs arrived incredibly early this morning, made some adjustments to the trumpet side CAD files and now printing in the cheap stuff/at high speed for a test fit! Just need to sort out the rest of the stuff. There is a 1.6 inlet in the post to me so hopefully I can hack that up/mill it flush/make flanges next week and then get it all welded the following week ready to assemble over christmas! ....Sounds realistic 
le sigh