2-TG N/A Cam Options - Real world results wanted

[trdee]

what's the rod/stroke ratio on a 2TG anyway?

[TheToyman75]

Jason,

The Light weight flywheel on the Colonel made a huge difference. Engine is stock unopened other than the 4kg flywheel.
I will never again fit a stock flywheel back into a Celica I plan on enjoying.

Vito,

Stock bore is 85mm, Mine and most turbo builds go to 87mm, big bore is 89mm
Stroke is 78mm with the 3T crank.
So my engine is around 1.12:1 Bore to stroke ratio and revs like a demon as you know

[trdee]

rod/stroke ratio is a different measure. need to know rod length to calculate it. I was asking because ollimpicblue was mentioning running a longer rod/shorter piston combo, which is done when you want to increase the rod/stroke ratio

for reference, the stock 4age rod length is 122mm with a 77mm stroke, which means a 1.58 rod/stroke ratio
my 9A has a 136mm rod with 90mm stroke so the rod/stroke ratio is 1.51:1

refer to other threads for the benefits/negatives of both a high and low rod/stroke ratio, but i doubt just running a longer rod/shorter piston in a 2TG will give you such massive gains that it is more worthwhile than a set of cams!!!

[TheToyman75]

Ahh ok - Rod length on a 3TGTE rod is 4.850" so 123.2mm
Stroke as mentioned before is 78mm

So Rod to Stroke ratio on a 3T crank and rods is: 1.58:1

[Snyper]

Very interesting to read through this thread...

Rod, can you give some ideas or details on where to get a lightened flywheel for a 2tg please?

[Celica RA45]

i always look to see what you guys run on your 2tg motors ,did a lot back in the early 80s and use to go to 4into 1 s as it made the motor get up and go quicker and made more low down torque and power ,but what we did was make up a spacer on the inlet manifold to move the carbies further out and use smaller ram tubes .from memory another 100mm and the ram tubes were 10mm .cams i tried a lot with 320 and 304 trd profiles but ended up using a cam that cam out of england that a rally driver was using per ekland i think his name was ,the cam was higher lift and made a lot more torque right across the rev range till 8000 rpm .set up on 44 mikunis.
the engine dyno had this motor making 155hp at the flywheel the group c corolla was making 165hp at 8000 with 48mm webbers 4into 1 exhaust with higher comp 11to 1 etc

[ollimpicblue]

i always look to see what you guys run on your 2tg motors ,did a lot back in the early 80s and use to go to 4into 1 s as it made the motor get up and go quicker and made more low down torque and power ,but what we did was make up a spacer on the inlet manifold to move the carbies further out and use smaller ram tubes .from memory another 100mm and the ram tubes were 10mm .cams i tried a lot with 320 and 304 trd profiles but ended up using a cam that cam out of england that a rally driver was using per ekland i think his name was ,the cam was higher lift and made a lot more torque right across the rev range till 8000 rpm .set up on 44 mikunis.
the engine dyno had this motor making 155hp at the flywheel the group c corolla was making 165hp at 8000 with 48mm webbers 4into 1 exhaust with higher comp 11to 1 etc

per eklund did,nt run higher lift cams , he ran the corolla in group A, this ment that the cams could run more duration but no more lift than the standard cams, i should no i have his engine in the garage

[ollimpicblue]

rod/stroke ratio is a different measure. need to know rod length to calculate it. I was asking because ollimpicblue was mentioning running a longer rod/shorter piston combo, which is done when you want to increase the rod/stroke ratio

for reference, the stock 4age rod length is 122mm with a 77mm stroke, which means a 1.58 rod/stroke ratio
my 9A has a 136mm rod with 90mm stroke so the rod/stroke ratio is 1.51:1

refer to other threads for the benefits/negatives of both a high and low rod/stroke ratio, but i doubt just running a longer rod/shorter piston in a 2TG will give you such massive gains that it is more worthwhile than a set of cams!!!

because the 2tg has domed pistons the burn rate on compression stoke is very slow, by increasing the rod length and shortening the piston means on compression stroke the piston slows down at tdc and lets the conbustion burn across the piston fare better, the difference it makes is unreal

[trdee]

the theory is sound but im still not convinced that the difference is that big in the real world, do you have any back to back dyno plots etc to show the difference? saying that it is a bigger benefit than a set of cams is a big call - that's 20kw++ you're talking about

[oldeskewltoy]

because the 2tg has domed pistons the burn rate on compression stoke is very slow, by increasing the rod length and shortening the piston means on compression stroke the piston slows down at tdc and lets the conbustion burn across the piston fare better, the difference it makes is unreal

works with the 4AG too - current 4AG Atlantic types uses 127.5mm long rods with pistons using a compression height of 25.02mm

[TheToyman75]

per eklund did,nt run higher lift cams , he ran the corolla in group A, this ment that the cams could run more duration but no more lift than the standard cams, i should no i have his engine in the garage

Now that is cool !!

[TheToyman75]

Very interesting to read through this thread...

Rod, can you give some ideas or details on where to get a lightened flywheel for a 2tg please?

Exchange rate is killer at the moment but I get the Fidanza ones out of the US - Usually via ebay. - Fidanza part number 130381. It is to suit the 3TC powered Toyota Ace.

http://www.ebay.com.au/itm/FIDANZA-A...JD94vQNoVeQLaw

[Celica RA45]

the cams that i have have more lift than the grp a cam s had.. these might have been experimental 1s there closer to 11.5mm of lift,by nicholson mc claren , trying to get a rod stroke ratio of 1.7 use to be ideal ,as it makes the piston dwell at tdc longer as was to make more power higher up in the rev range ,have been doing it for ages ,also by compacting the ring pack closer and using a smaller pin will help as well
i have been doing this with the beams motors for ages changing rod stroke ratio from std 138mm and up to 149mm rods and also off set grinding cranks to change the stroke back from 86 to 84mm stroke

[73GTV]

per eklund did,nt run higher lift cams , he ran the corolla in group A, this ment that the cams could run more duration but no more lift than the standard cams, i should no i have his engine in the garage

HKS

[Snyper]

Thanks Rod, price isn't too bad considering the price of some others seen online, but then chuck on the postage.
Something to look into.
What was the dyno results of your 262 motor, did you have any?