Help Alex figure out if a carb will fit =)

Fran Hall RCR

Moderator
We just made some new scoops for the race car...similar to the ones on the #18 car but a little taller...not as an aesthetic part but for functionality..

 
It seems almost everybody wants some form of scoop(s) instead of a rear window, heh.

Unless ya'll want to step up to contribute to design costs, hopefully you like what style/etc.... I'll be choosing when the time comes :drunk:

How much vertical clearance do you have from the top of the carb inlet flange to the closest point of the lexan rear window?
I have approximately 2 1/2'' from the forward most (towards the front) fuel bowl to the rear clip with a 4150 carb. If I go to a dominator that'll be closer to 1'', so not a whole heck of a lot!
 
I have one question that I planned on addressing with Fran once I place my order ... The venting of the radiator is right in the path of the roof scoop which means that the HOT air will flow right over the windshield and into the scoop which I would assume is not the greatest thing. I am sure that some sort of diver-tor could be fabed up ala GT40. I am curious because that was one of things that I was warned about when looking into an Ultima by every owner. Those that have driven their SL-C's has this been an issue for any of you or have you all just left the vent there for aesthetics?
 
Damian,

The roof vent is probably better suited for cabin air which is what I intend to do with it. That said, you can tunnel it to the engine bay with some modification to the firewall, etc.
 
I can see that being a great option and one that I would love to do once I start my build. My only concern is the hot air from the radiator since that's where mine will be. I have all but given up on the idea and now plan to just put a camera and radar detector / diffuser in there unless I can figure a way to divert the hot air like I said ala GT40. If anyone has any real world experience with this please chime in as I am going of hear say and theory and we all know that reality can be very different.
 

Howard Jones

Supporter
2.5 inches will work as it will allow for the same area as the 5 inch diameter carb inlet area or aprox 16 sq inchs. If you look at my cardboard box you can see the inlet going forward towards the filter area is aprox 7 X 2.5 inchs. That gets you about 17 square inchs. My idea is to continue to increase the cross section of the box as it progresses towards the filter itself. This should prevent restriction to flow that would be in excess of the filter element itself. The filter was selected using the calulator on the K & N website.

1 inch will be very tight and I don't think it will work for you. On the other hand I don't see why you can't get enought HP from a 850 DP. That will allow you to work with a 4150 carb.
 
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2.5 inches will work as it will allow for the same area as the 5 inch diameter carb inlet area or aprox 16 sq inchs. If you look at my cardboard box you can see the inlet going forward towards the filter area is aprox 7 X 2.5 inchs. That gets you about 17 square inchs. My idea is to continue to increase the cross section of the box as it progresses towards the filter itself. This should prevent restriction to flow that would be in excess of the filter element itself. The filter was selected using the calulator on the K & N website.

1 inch will be very tight and I don't think it will work for you. On the other hand I don't see why you can't get enought HP from a 850 DP. That will allow you to work with a 4150 carb.
I'm still up in the air regarding the carb - 4150 vs dominator.

According to VE calculations, 502cid, 6800(aprox) rpm, 90% ve is around 900cfm; 100% ve is around 1000cfm.

They make a 1050cfm quickfuel 4150-style carb, so I could stay with the 4150, but I wonder if the 1050cfm dominator wouldn't be better given the size of the motor? (more air flow, etc...)?
 

Howard Jones

Supporter
On a 2 1/4 min lap in my GT40 I bet I'm not on the rev limit more than 6-8 sec. And I have 350ish HP! What percentage of the time do you expect to have your 502 at 6800 RPMS with with your foot flat to the floor? The 850 will be fine........trust me.

Build the car light and to handle and stop, don't worry so much about, what will be evident in the end is, way too much power................IMHO....
 

Doug S.

The protoplasm may be 72, but the spirit is 32!
Lifetime Supporter
Build the car light and to handle and stop, don't worry so much about, what will be evident in the end is, way too much power................IMHO....
I agree with Howard :thumbsup:....the best advice I ever got on this forum was something to the effect of: "...save your money on engine mods, 350 HP is enough. Spend your money on big brakes, they'll never catch you."

Makes sense to me :idea:

Cheers from Doug!!
 
I agree with Howard :thumbsup:....the best advice I ever got on this forum was something to the effect of: "...save your money on engine mods, 350 HP is enough. Spend your money on big brakes, they'll never catch you."

Makes sense to me :idea:

Cheers from Doug!!
That could be, but I need to make sure I have more power than a Zonda R...just...because :D:drunk:
 
Hey, let the poor guy have as much power as he wants, if he has enough ( or some might say tooo much ) he will get a burial or cremation ( possibly both-but not neccesarily in the correct sequence ) with the package for no extra charge:)...
 
Ooooooo, when researching carbs one of my friends suggested looking at a pro-systems SV1 carb. it's what he uses on his drag car and he's always raving about it (the carb)

I looked at it and it seems like it might be a winner in this case:

- responsiveness of a 4150 style carb
- power gains of a 4500style carb
- 1/2'' shorter than a 4150carb

Mmmmm



No transition slots as you can see (only 1 throttle plate thingie), so basically your choices are 'idle', or 'GO!'. Mmmmmm, that's my kind of carb!
 
On a 2 1/4 min lap in my GT40 I bet I'm not on the rev limit more than 6-8 sec. And I have 350ish HP! What percentage of the time do you expect to have your 502 at 6800 RPMS with with your foot flat to the floor? The 850 will be fine........trust me.

Build the car light and to handle and stop, don't worry so much about, what will be evident in the end is, way too much power................IMHO....
Especially given the light weight enables the builder to select a cam/tune that sacrifices torque to gain HP.
 
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