i would like to know if u want more torque out of your motor and running carb u have long runners. How long of runners can u have and can too much lose power.

 

Longer runners will add low end power at the expense of top end power. Your car comes with the best length for average street use. If you want to make more low end power just be aware that your car will be slower overall. Headers are a good way to add some power (high and low). When you change runner length you also need to rejet the carb. Generally you don't want the runners too long on a carb. Fuel will fall out of suspension really quickly through long runners on a carb'd car. If you had fuel injection you could get away with much longer runners and not worry about this problem. I'd stick with what you got. If you just want a little more low end and power off idle then I'd suggest a Camden Supercharger. (Please no debates on this!)

 

Ummmmmmmm

Nope. Oversimplification there which has ended up with the answer coming out with a number of glaring errors.

I'll be back with an explaination later

Bill

 

Please do explain that statement! I admittedly am more accustomed to fuel injection. I really didn't want to write a big long technical book on an already overly written about topic on this forum again.

 

Written about yes. Concluded No. There are still many questions to be answered.

To put things in perspective. I have run a 45DCOE on a T2 lower, giving a total inlet length of 24". badly port matched on an RX4 block with a good header I was getting 140HP at the wheels on an eddy dyno with a 3.62 diff. On a dyno jet with a 4.1 diff that could be a heap more.

Ran great up to 6000RPM where the power just fell off due to runner length. Started on freezing mornings without a choke. So the car ran like a scalded cat up to about 110 mph and then gave up on accelerating.

With a rotary you can pretty much position the torque curve where you want it by adjusting the inlet length. The secret is to decide what you want the torque curve to look like.

If you look at the article on the TWM website and convert the power graphs to torque curves then you get some interesting plots. For example the Dellorto and EFI torque curves are identical, but offset by 500RPM. One gives 16HP more at 5000RPM, the other 20HP more at 8200. Which is better/faster for you depends on the compromises you want to make.

Interestingly as well the holley really needed a longer inlet.

So ya pays ya money and makes ya choice.

Bill

 

I agree with that. I was over simplifying things. I am just going under the assumption that the stock Nikki carb is being used and that only a different intake manifold wants to be used. From what I've seen, its hard to make the Nikki work in different applications. Have you found this to be true also? I'd love to find out how that carb can work in a different setup. He never mentioned the Nikki though so I don't know why I am assuming he is using one.

Bill: I always love discussing things with you, even if I'm wrong (never! j/k ). You are truly one of the most knowledgeable people on here and no matter how much I think I know you have always given me more to think about. Damn you!

 

i am using a 48dcoe with the tii manifold just to let u guys know.

 

I wouldn't say knowledgable, I just like to understand where numbers come from, which means I often like to go back to first principles. However this is often theory, and as we know the engines never seem to read the text books :-)

48 DCOE. Hmmm. Unless you are mainly racing that may be on the cusp of becoming a slight pain on the street. If it were me I would put the smallest chokes in (40mm IIRC). I would also consider trying F3 emulsions. These are identical to the F11s most use BUT are thinner, so the main circuit will come in a little earlier and make it easier to tune the transition. IMHO mandatory if you go to larger chokes, but YMMV

That config should fly as long as you don't want to rev to 8000.

Bill