Surfriding running dual 38s on larger motors?

masterblaster

masterblaster

X-H2
im running a 830cc stroker with a few diff carbs 46 and 48 novi and fs,they all suck major fuel,in our ride area I need longer runtime im not carrying fuel tanks. I have a extra mount plate for a R&d 2 part intake,are there any kind of adapters that would allow the 38s to bolt up to this kind of intake,id like to be able to pull quick change outs to the 48s when im riding other places?

Any idea what 38s would jet at for this big a motor,Im sure they will be sick crisp off bottom with this kinda vacuum..... losing some power will be worth it. any idea how long a ride time 38s get with a 800 cc motor,i was getting 2.5 hours with them on a 701
 
2

2XLR8

X-
Why not just run stock unmodified 44 carbs. Should give you closer to the performance you are used to with the 46 and 48 novis compared to the 38's plus they will fit on the same plate.
 
masterblaster

masterblaster

X-H2
I have seen some buds run 44s and they suck alot of fuel on larger motors as well,it would be a minimal gain of ride time,the main goal here is to get back over the 2 hour ride time,I have no problems with tuning oem carbs,they seem to meter even better for less fuel consumption,and a linear pull even if they are a little down on power.
 
masterblaster

masterblaster

X-H2
I already have a few 2 part twin manifolds and want to be able to switch back to big carbs easy.dont really get the single carb on a 62t case,other than being a little smoother.smoother in most cases = less power....kinda defeats the purpose. 38+38 =76 plus alot more response and great fuel consumption run times.

I have ridden 62t/61x 785 big bores in st marten that fab setup with single 48 that ripped smooth power,so i suppose they have their place. it seems that a 830 running the eqiv to a 76 single would be pretty capable ?
 
Last edited:
junkyardj

junkyardj

┌∩┐(◣_◢)┌∩┐
Location
barrie ont. canada
i have a set of clearenced 38's that a ran on a ported760 with TL and a dry pipe and the thing ripped but i dont know how they would do with a BB stroker.. i have that XS ADA motor with XS 46's and im supprised to say the ski is really good on fuel(av gas)

i can check my book for the jetting if you want to use it as a start
 
masterblaster

masterblaster

X-H2
I get pretty decent run time out of my 46s,but no where near what the 38s got,but they were on a smaller cc motor.I think it will enteresting to see what they will max out at on this 830cc setup,keeping in mind I dont need anything but low to lower mid performance to surf ride,they may well be great for this purpose. If that doesnt work I think flashfx has some good ideas with decreasing the size of the metering holes in the 46s to meter fuel smoother on the transition circuit that would help them be more linear and use less fuel through this long azzz slow wake.Ill try that next

what is your current jetting,ill compare it to mine,and what is your aprox ride time on that setup?
 
Dustin Mustangs

Dustin Mustangs

uʍop ǝpıs dn
Location
Holland, MI
Two 38's are equivalent to one 54 (you would add the areas, not the diameters). Comparing the cross sectional area like this doesn't take into account all the extra obstructions in a stock 38's bore or the fact that you are dealing with over 40% more surface area so realistically an equivalent flowing single would be much smaller than 54.

You might want to look into the Jetworks taper bore 38's. Art says power wise they are equivalent to 44's and I am getting some crazy long run time on them with what is still a bit of a rich tune. Significantly longer than when I was running a single 44 on some x cases and I am making way more power now and have a bit more displacement.
 
junkyardj

junkyardj

┌∩┐(◣_◢)┌∩┐
Location
barrie ont. canada
masterblaster said:
I get pretty decent run time out of my 46s,but no where near what the 38s got,but they were on a smaller cc motor.I think it will enteresting to see what they will max out at on this 830cc setup,keeping in mind I dont need anything but low to lower mid performance to surf ride,they may well be great for this purpose. If that doesnt work I think flashfx has some good ideas with decreasing the size of the metering holes in the 46s to meter fuel smoother on the transition circuit that would help them be more linear and use less fuel through this long azzz slow wake.Ill try that next

what is your current jetting,ill compare it to mine,and what is your aprox ride time on that setup?
Click to expand...

with my clearenced 38's
1.5 n/s
115 g
85p fatt
137.5m
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Dustin Mustangs said:
Two 38's are equivalent to one 54 (you would add the areas, not the diameters). Comparing the cross sectional area like this doesn't take into account all the extra obstructions in a stock 38's bore or the fact that you are dealing with over 40% more surface area so realistically an equivalent flowing single would be much smaller than 54.
Click to expand...

This doesn't really work out. Dual 38s are not "equivalent" to a single 54 simply because each of the 38s is feeding one individual cylinder. Even the single 54 carb would feed only one side at a time.
At no time do the 38s combine to feed one side or the other.
 
chriselmore_1

chriselmore_1

high on resin
Location
san jose ca
hmmmm. That's an interesting point matt. Makes me reconsider my choice to switch to dual carbs. Now I'm not sure if I should stick with my single taperbored 46....
 
junkyardj

junkyardj

┌∩┐(◣_◢)┌∩┐
Location
barrie ont. canada
Matt_E said:
This doesn't really work out. Dual 38s are not "equivalent" to a single 54 simply because each of the 38s is feeding one individual cylinder. Even the single 54 carb would feed only one side at a time.
At no time do the 38s combine to feed one side or the other.
Click to expand...


doesnt the crossover change that?
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
You have one dedicated carb per cylinder with duals. Carburetion its cleaner because you don't have the overlap you got with a single.
The intake runners are shorter and more direct with duals.
 
You must log in or register to reply here.
Top Bottom