Crossflow Build Advice

[wagoon 2,429]

I know I keep referencing my roller cam build but it is using 29.3cc dish pistons which is the biggest dish with a cylinder head that brings comp to 10.3-10.5. If I added a different head then it would bring the comp way down and I could easily run a turbo. Its fine to transfer over the parts to the new head but there is a fair chunk of money in porting, valve size, valve seat and then seals etc. which you will throw away when changing heads. And as said if your going to go serious turbo then there is some serious upgrades needed. But still comes back to do you want an engine now or when your off your P's

[Nath 1,975]

Will stick with NA for now.

 

If I want one later, I figure if I have enough money for a shiny new turbo setup then I have enough to sort out a different head to go with it. And at least that way the bottom end will also be stronger as well, instead of just slapping a turbo on a stock motor.

[eattsie9 350]

Out of curiosity Anybody got a rough idea of what hp/torque figures and 1/4 times the build nath posted original would pull?

[Nath 1,975]

Seeing as I'm building it, it would probably throw a rod about 200m in.

[eattsie9 350]

I'll have to wait and see what you achieve I'm looking at a similar build

[slydog 7,873]

Jase Stoodley ran this combo for a while before moving on. Take note those who want realistic reliable pump fuel power all for sensible money.  

 

Block: 80da bored & honed .030
Crank: 250 ground & balanced
Rods: 250 machined balanced and 302w ARP bolts fitted
Pistons: ACL 21cc dish - combined with a 50 odd cc head was about 9.5:1 comp.
Cam: 230@50 530lift hydro - great cam for these motors!
Head: open chamber carby unmarked ported, 1.85" in, 1.55" exh valves, turned out it flowed 320hp
Springs: crow 7333 doubles - head needs machining for these.

Other parts included rollmaster chain, yella terra street terra bolt ons, crow pushrods, romac balancer.

Used to run a ultraflow manifold with a 500 holley went well but changed over to a cain and 600 vacuum secondaries and what a difference.

Was running a Hall dizzy with a MSD 6AL and MSD digital timing computer- the equivalent now would be a 6AL-2programmable running 36deg total timing.

Used a 2200stall in a c4 with 3.7 rear gears.

the car was a full street car cortina ran 13.6 @ 100mph then 13.3@103 when i changed to the 600vac and made 200rwhp

[NZXD 2,328]

That's s decent set up, take note of this Nath.

[Nath 1,975]

Cheers Sly, notes are definitely being taken.

 

Once I get all the main bits here (new head/cam combo, extra bottom end) then I can start sorting the other stuff out. A holley is not out of the question either.

 

 

Here's a question for you guys:

 

I have both a 3.3 and a 4.1 bottom end. Would it be worth using the 200 block (turning it into a 4.1 though), or just start with a 250 block to begin with? Both of them would be getting bored and honed anyway. Would be nice to keep a matching numbers car, if it's only slightly more of a stuff around then I'm happy to do it.

[NZXD 2,328]

I personally would remove the original 3.3 and set it aside, start work on the 4.1.

[wagoon 2,429]

Love that post Sly, proven real world results cant be ignored. What I take from the above is that a 2 barrel really is not that far behind a 4 barrel on an engine like that. Seeing the 60 foot times of both carbies would be interesting as it might tell you a bit more about how much different the 2 carbies would be on the street.

Regardless that is mid to low 13 second setup in a car that weight just over 1200kgs. The fact there is nothing exotic in that engine and going off what I paid for machining last year that engine would be ready to assemble for easy under $4000 and you could make that price drop a bit more if you tried. Add exhaust, carby and inlet and away you go.

[wagoon 2,429]

Blocks are the same just the crank rods and pistons are different. So keep the original block and put the rotating assemble out of the 250 in it. Or put the whole 200 aside and use the whole 250 block.

[slydog 7,873]

Remember that was Jase Stoddleys combo guys so thank him. He did many many km's testing and racing his stuff so we know it doe's work.

 

Again all this info has been there all along and has been used not suggestions,I can't emphasize that enough here. He is not saying this or that should or I would use it is "from his experience". Remember that when people say they "would use". A few of us on here have done all this many times before so listening to people who do and have is the best and safest way.

 

Thats all that needs to be said really.      

[Nath 1,975]

Works for me. I'm not trying to re-invent the wheel.

 

I'd be more than happy with a 13 second crossy....

[NZXD 2,328]

I'd be happy with 13 seconds too. I thinking I should be able to sneak in.

[slydog 7,873]

I'd be happy with 13 seconds too. I thinking I should be able to sneak in.

 

I reckon you will be right bro.

[Nath 1,975]

I'd be happy with 13 seconds too. I thinking I should be able to sneak in.

Might be a bit fast for the mrs though.

[NZXD 2,328]

My issue is that I will worry about breaking something if I lean on it too much, crunch crunch goes the single rail haha.

[NZXD 2,328]

 

I'd be happy with 13 seconds too. I thinking I should be able to sneak in.

 

 

Might be a bit fast for the mrs though.

 

I only do scarecrows Hahahaha

[slydog 7,873]

My issue is that I will worry about breaking something if I lean on it too much, crunch crunch goes the single rail haha.

 

The rail will only break the selector usually but other wise there as big as a top loader in side. I'd have a rail over a T5 everyday of the week. Mine use to break sun gears before it broke gearboxes. 

[TF_250 398]

Love that post Sly, proven real world results cant be ignored. What I take from the above is that a 2 barrel really is not that far behind a 4 barrel on an engine like that. Seeing the 60 foot times of both carbies would be interesting as it might tell you a bit more about how much different the 2 carbies would be on the street.

 

 

Went into the vault for you, 2.03 60's for both carbs mate!! the 500 was a good carb but the 600 vac had way more top end, 3mph is a lot with a carb change. 215/60 nankings 1280kg car

 

 

Jezz 2.03 60'!!! now I do 1.66 and I'm not happy!!!!

[wagoon 2,429]

Single rail's are used behind solid roller cam crossflows running on methanol in speedway cars. They don't exactly roll on and off the throttle easy in racing

[NZXD 2,328]

The guy that rebuilt the box completely said they are tough but have weak shifting capabilities. I'm not that hard on my gear anyway.

[wagoon 2,429]

Thanks Jase your a champion. I didn't know if the 4 barrel would help it get off the line a bit better as well as top end. Your right that 3mph and 0.3 sec is huge just with a carby change.

[Nath 1,975]

The guy that rebuilt the box completely said they are tough but have weak shifting capabilities. I'm not that hard on my gear anyway.

Grind it till you find it!

[LJDB 103]

if you wanna do it on the cheap get on ebay. I've picked up plenty of bits and pieces. i payed $80 for 2 falcon single rails, $150 for cortina manual conversion including another single rail, $180 for 2 250 xflow bottom end 1 reco and another that's balanced with a 220@50 520lift cam and lifters to suit. $400 for a redline 4 barrel manifold with a 570 street avenger. $150 for a 28 spline 3.45 complete diff (i only wanted the center). the hard part is finding a good modified cylinder head to suit your desired compression ratio on the cheap but if you have plenty of time you can try port one yourself as theres heaps around to play with. ive picked all this up over a year or so mainly as spares if mine decides to let something go.