Ford Crossflow Upgrades In A Vixen?
Discussion
Over the next month the Vixen engine will be taken out for a full refresh ready for the start of the new season in late March.
Current engine spec is :
Stage 3 head
1760cc
Forged pistons
A2 cam
Twin 40's
Light weight steel flywheel (4.6kg)
The rest is pretty much standard (rods, crank, valve gear etc) but properly balanced. For info, the car is used both on the road and in competitive hillclimb events.
The engine has always felt really nice for both road & track but having never driven any different spec engines, I have nothing to compare with. I don't need more power (134bhp, 131ftlb) but a wider torque curve would be good. I don't want to raise the rev range above 6,500, but strong low down torque thru to 6,000 would be perfect. I also want to 'bullet proof' it, where reasonably possible.
The items I'm thinking about include:
Steel rocker posts & shaft ?
Roller rockers ?
A more modern cam profile ? Kent 234 seems a popular choice for good power & torque across the range
Steel Maxpeeding rods ? - lighter (& stronger) so should make a more free rev'ing, responsive engine
I would be interested to hear of experience/suggestions.
Moto
Current engine spec is :
Stage 3 head
1760cc
Forged pistons
A2 cam
Twin 40's
Light weight steel flywheel (4.6kg)
The rest is pretty much standard (rods, crank, valve gear etc) but properly balanced. For info, the car is used both on the road and in competitive hillclimb events.
The engine has always felt really nice for both road & track but having never driven any different spec engines, I have nothing to compare with. I don't need more power (134bhp, 131ftlb) but a wider torque curve would be good. I don't want to raise the rev range above 6,500, but strong low down torque thru to 6,000 would be perfect. I also want to 'bullet proof' it, where reasonably possible.
The items I'm thinking about include:
Steel rocker posts & shaft ?
Roller rockers ?
A more modern cam profile ? Kent 234 seems a popular choice for good power & torque across the range
Steel Maxpeeding rods ? - lighter (& stronger) so should make a more free rev'ing, responsive engine
I would be interested to hear of experience/suggestions.
Moto
Have you got a copy of this Moto
https://amzn.eu/d/aLhJDUE
It’s very detailed if probably rather out of date
Also Burton Power has a good guide
https://amzn.eu/d/aLhJDUE
It’s very detailed if probably rather out of date
Also Burton Power has a good guide
Yes thx, I got a copy 2 weeks ago and as you say it's very, very good. Written in a style and at a level that was perfect for me. Most of my current thinking is based on it's content.
What I'd now like to know is what other Vixen owners have done and their experiences. I have a mindset that what is good for a 600kg Caterham or an Escort for example may not be best for a Vixen.
Moto
What I'd now like to know is what other Vixen owners have done and their experiences. I have a mindset that what is good for a 600kg Caterham or an Escort for example may not be best for a Vixen.
Moto
Hi Moto,
If it's a Burton head, I'd contact them to find out if they have dyno charts for an engine with a "stage 3" head in which they tested the 234 and 244 profile "back to back." (Obviously with carbs being optimised in each scenario.)
I'd also talk to them about different ratio roller rockers. You can argue roller rockers either way. The Anti school of thought says that the needles can come out of the bearings and destroy the engine. I'm of the opinion ththe reduced valve stem and guide wear makes them worthwhile.
Also, consider the ignition system. "Better" means smoother, and less unwanted vibration translates to fewer problems.
To "bulletproof" an engine, I'd go with all forged internals, including H-beam rods. Just as important, make sure that the hardware is the best available in all critical areas. SPS CARR for rods, ARP for head, flywheel, main caps, . . .
Good luck!
On edit: I'd also get someone to run the final combination through PipeMax, and make an exhaust system based on what that spits out.
If it's a Burton head, I'd contact them to find out if they have dyno charts for an engine with a "stage 3" head in which they tested the 234 and 244 profile "back to back." (Obviously with carbs being optimised in each scenario.)
I'd also talk to them about different ratio roller rockers. You can argue roller rockers either way. The Anti school of thought says that the needles can come out of the bearings and destroy the engine. I'm of the opinion ththe reduced valve stem and guide wear makes them worthwhile.
Also, consider the ignition system. "Better" means smoother, and less unwanted vibration translates to fewer problems.
To "bulletproof" an engine, I'd go with all forged internals, including H-beam rods. Just as important, make sure that the hardware is the best available in all critical areas. SPS CARR for rods, ARP for head, flywheel, main caps, . . .
Good luck!
On edit: I'd also get someone to run the final combination through PipeMax, and make an exhaust system based on what that spits out.
Edited by Slow M on Sunday 4th January 20:09
If starting again, I agree AX block being the best route. However, my 711M block was taken out to 1760 (85mm) over 40 years ago and is still going strong, so suggests it's a good block with no reason to change.
SlowM - helpful response thx. I have just spoke with Burton re any stage 3 head/cam dyno data, but alas they have nothing. I also talked to Kent - very helpful with useful advice but no dyno data. It therefore was quite subjective but they recommended the 234.
Regards roller rockers, as you note it seems to be 6 good reasons for every 6 reasons why not. They do seems to have more positives with the old cam profiles such as my A2 (low lift, gentle ramps) compared to more modern profiles such as the 234 (high lift....). Low lift cam put less stress on the rollers so less likely to fail.
Ignition is definitely something I need to think about more. as you say "better" is smoother. I'm not able to go 3D so limited to points or electronic 2d modules. Currently running Lucas 43 with Accuspark which is cheap but works OK. Maybe more upmarket items such as Aldon/Ignitor. 123 or Lumenition would be "better"?
Agree on all forged internals but as only revving to 6.5k it'll be down to £'s to be worthwhile. Maxspeeding rods 40% price of top brands and all reviews suggest OK. I do quite like OE setup if I could find a set with little wear to polish/lighten/balance etc. Just not available new anymore.
ARP definite thumbs up. Exhaust already been built for car by Maniflow.
Moto
SlowM - helpful response thx. I have just spoke with Burton re any stage 3 head/cam dyno data, but alas they have nothing. I also talked to Kent - very helpful with useful advice but no dyno data. It therefore was quite subjective but they recommended the 234.
Regards roller rockers, as you note it seems to be 6 good reasons for every 6 reasons why not. They do seems to have more positives with the old cam profiles such as my A2 (low lift, gentle ramps) compared to more modern profiles such as the 234 (high lift....). Low lift cam put less stress on the rollers so less likely to fail.
Ignition is definitely something I need to think about more. as you say "better" is smoother. I'm not able to go 3D so limited to points or electronic 2d modules. Currently running Lucas 43 with Accuspark which is cheap but works OK. Maybe more upmarket items such as Aldon/Ignitor. 123 or Lumenition would be "better"?
Agree on all forged internals but as only revving to 6.5k it'll be down to £'s to be worthwhile. Maxspeeding rods 40% price of top brands and all reviews suggest OK. I do quite like OE setup if I could find a set with little wear to polish/lighten/balance etc. Just not available new anymore.
ARP definite thumbs up. Exhaust already been built for car by Maniflow.
Moto
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