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Fitting 4-1 Comp Header in 1991 Caterham with Crossfow


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Hi All,

 

I am original owner of a 1991 Caterham 1700 Supersprint with a Ford Crossflow engine and Ford T9 5 speed, Car is left hand drive.

 

The engine is almost finished with a mild race rebuild, part of the change was fitting a Caterham supplied 4-1 competition header in place of the 4-2-1 system that came with the kit.

 

The 'bundle' of pipes exiting the body is significant, I realize the hole in the skin needs to be enlarged. There is also the steering column to deal with and a diagonal brace that seems to be at least partially in the way.

 

Has anyone made this change and dealt with the modifications to make it all fit. Caterham UK says it will fit...LOL if it doesn't

 

Appreciate any help or advise from the group.

 

John

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John, don't know about the crossflow. But widening the exhaust hole is easily done with some tin snipes or a dremel. Are you planning on racing the caterham? I always understood that the 4 into 2 into one was better for Mid range torque and hp, and that the 4 into 1 was better for top end. At least that was the claim for my Rover K series.

 

On the K series there were definitely a LHD and RHD spec exhaust pipes as the steering column definitely is close on the K series due to the way the engine is canted over to the left. Hopefully you have the correct ones. Maybe KitCat or one of the other current or former Crossflow owners will chime in. Good luck. Tom

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Tom, Thanks for the thoughtful comments. The engine build is less 'mild' than I alluded to, it's actually close to full race and the car will remain a track day car other than some driving in the rural area around my shop. If I turn left and go up the Sierras, there is not a stop all the way to Nevada.

 

Caterham does say it's the right part but until I start fitting each pipe and trimming the panel, it is still a concern.

 

Any help from KitCat or other Seven owner that has made this modification is much appreciated.

 

Tom, photo is my car at Laguna, your car looks pretty radical, I have never seen such a large wheel/tire combination. Is it set up for road race, auto cross...or?

 

Thanks,

 

John

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Steve,

 

That would be great. I do appreciate it. I do have questions...

 

Did your car come with the 4 - 1 or did you convert it from the 4-2-1 header?

 

What is the year of your chassis? Mine is a 1991 with the long cockpit feature.

 

Can you fit each individual pipe with the steering column in place or do you have to pull it and (hopefully) thread it back in place though the bundle of pipes without fouling

 

Does your car have the diagonal cross member from the upper and lower chassis 'rails'?

 

Can you take a photo from both inside and outside?

 

Can you mark with tape on the outside where the chassis members are so I can get an idea on how to enlarge the hole without going too big and making a mess.

 

In light of Tom's comments, how do you find the 4-1 header work with your engine...or better yet, what is the build out?

 

My engine...45mm Webers, largest valves, roller rockers, A6 cam, 84mm CP pistons, 11.75:1 CR, Dry sump, new Scat Crank, lightened rods

Engine is going together now, soon to be dynoed.

 

Thanks Tom,

 

John

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Sorry, no shots of engine bay from that angle. And car is long gone.

 

My memory is steering shaft space was really, really tight. Someone here with an x-Flow mite be able to snap a picture showing fitment.

 

I will be interested in your dyno results. As BBall may note, his higher hp X-flow rebuild was not without its trials and tribulations. Maybe he will fill you in?

 

Am also slightly jealous of your driving roads. When I make a left out of my driveway I then have to make many more, both right and left, to get to anything without a stop sign.

Edited by Kitcat
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KitCat

 

Off topic but...I live in the Gold Country on the Western slopes of the Sierra Nevada range at about 2,500' elevation. Turning left I climb to the pass at 9200' and then down the Eastern slope to 4,000' elevation. There's a 'T' at the end, turn around and the same unencumbered road home. As long as you don't do something foolish, the CHP leave you alone, especially if you are a senior. 5mph over the 55mph speed limit, try not to slow for any turn although hairpins are a bit more tricky. It took me 40 years to get out of suburbia and now I am in driving mecca

 

When the engine is dynoed, I will post full build specs and dyno results. I could have gone Zetec or some other more modern engine, but somehow I just felt the Ford crossflow was right for the car...and for me. In spring I should be back on track hoping to take a few seconds off my lap time at Laguna and Sears

 

This is a great site, I am thankful for the interaction from like minded car loving people.

 

John

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Tom, photo is my car at Laguna, your car looks pretty radical, I have never seen such a large wheel/tire combination. Is it set up for road race, auto cross...or?

 

Thanks,

 

John

 

John, I originally autoxed the car for about 8 years and when I started doing track days, I used the same set up. Only thing I have changed is to go to a slightly taller tire which more closely matched the circumference of the original Avon CR500's the car came with. That allowed me to get a little more top end on the track. The balance is perfect IMO and other racers who have driven it seem to agree.

wide tires.jpg

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John

 

I have 4 into 1 Crossflow. I can email you a few pics if you PM me your email address. Hard to see for sure even on the pics but may help.

 

Looks as as if starting with the center pipes first to get the hole in approx place may work and enlarge outwards. Should be able to estimate from the center ports on head to get distance to body. Rather think it won't be that straightforward though.

 

Martin

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John - Hope these photos help. The pipe from cylinder 1 intersects the body 6" back from the bolt in the engine mount which attaches to the frame.

 

Other answers. It came with the 4-1 exhaust, so don't have anything to compare it to. It's a 1998 with the diagonal cross member. Can definitely fit the pipes without removing the steering column.

 

My rebuild is a bit milder than yours. 40mm webers, large valves, port work, roller rockers, 83.5 pistons, 10:1 CR, SCAT crank, wet sump, standard rods, Kent 244 cam. Dynos really vary, but think it made around 158 hp (adjusted) at the crank at about 7200 RPM. Can't find my dyno sheets right now, so working from memory. Engine builder was surprised, to be honest.

 

Steve

 

IMG_1666.JPGIMG_1650.jpgIMG_1649.jpgIMG_1648.jpg

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I've got a xflow in a '99 Classic chassis with the 4-1 side exit.

 

It is tight, but it does work, at least if the primaries, engine location, alternator, etc. are all the standard Caterham-spec parts. As I recall, the main thing is you'll end up playing a game of fiddle-f*** to get the column to simultaneous clear the 4 primaries and the bottom of the alternator housing, while not binding the U-joint at the steering rack. You may find you need to tweak the orientation of the steering rack and/or the bulkhead bearing for the upper steering column. I found it helpful to put the front of the car on jacks so I could easily feel for a bind in the u-joint while rotating the rack bit-by-bit to clear the alt. housing and primaries.

 

 

Dave

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Thanks both Steve and Dave for the helpful information and photos. All my parts are Caterham including the header which I got from Caterham, UK. Steve, I assume your individual pipes are one piece with heat coating inside and decorative chrome plating outside the body. Does the alternator hold up to the heat with the header pipe so close? I have a fiber heat shield over mine that will likely need to be removed

 

Steve, my builder targeted 150 HP and 135-140 lbs of torque which I would be happy with, perhaps we are a little conservative in the estimate. I will share the results after the dyno day.

 

Thanks again for the help, this is going to be fun.

 

John

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Steve's highly polished car and exhaust is result of a lot of hard work. I very seriously doubt that it is a "chrome" plating. You have to see the car in person to really appreciate the quality of his work. And wear your sunglasses, or risk going blind. :cooldude::cooldude::cooldude::jester: Tom

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John:

I found a shot of my '97 Cat showing a single exhaust pipe coming through the cutout. I must have had a less aggressive header set up.

My X-flow dyno'ed at 95 hp, 93 lbs torque.

Since the Cat tank holds 8 gallons, and gets abt 12-16 mpg (when driven properly:)), the range is somewhat limited. I used to carry a 2 gallon gas container for emergencies and used it a few times. If your blatting area is as remote as it seems, this mite be an issue. Also, can you get 93 octane, or just 91?

Speaking of X-flows, I have discovered via owning one of each, that it is easier to get parts for the X-Flow than the Zetec SVT. Ford has stopped making SVT parts (as opposed to standard Zetec parts, which, unfortunately, are mostly not interchangeable with the SVT engine).

I look forward to pix of your car out amoungst the mountains.

Edited by Kitcat
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KitCat

 

We can only get 91 Octane at the pump but after the dyno run we will determine the best fuel, likely 110 for the track. I figure to keep a 55 gallon drum in my shop for the Seven.

 

Mountain runs in my Seven will be limited to climbs to the summit and then back, due to the fuel range and to some degree the wear and tear on the driver. I have an Elise for more adventurous runs. The ultimate Elise drive is a lap of summit passes (there are 4) which I have yet to do but is on the bucket list. Start on Sonora Pass (CA 108) over the summit then down to CA 395. Take 395 north to Ebetts pass (CA 4) or south to Tioga pass (CA 120) back over the mountain, then CA 49 south or north back home. CA49 on the Western slope and CA 395 on the Eastern slope connect all 4 passes. All roads are well marked and maintained, have passing lanes and turnouts. California may have regulations that are a burden on car owners and make them expensive to operate, but we do have some great driving and scenic roadways.

 

Thanks everyone for your feedback...when my Seven is back on road again I will send some photos, feedback on the build and dyno results. Also...after seeing the photo of Steve's car I need to spend a few days polishing the body which still won't look anywhere as nice as his car, amazing!

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  • 10 months later...

Hi All,

 

I am embarrassed to say it has taken this long to get this project done. I made so many changes it seems everything was improved or upgraded from when I built the car 25 years ago. I cut no corners in the project and I am totally pleased with the result. The engine was standard Caterham Super Sprint Crossflow Cortina now significantly upgraded. Engine Dyno results: 160HP at 7,200 RPMs, 125ft/lbs of Torque at 5,600 RPMs. The header was difficult to fit, no. 2 and 3 pipes needed a little concave indent with careful hammering made more difficult as the indent was where there was a pipe connection weld. The car was originally fitted with a 4-2-1 header so the opening in the side had to be opened up which was a challenge. The hole went from a circle to a parallelogram with rounded corners, I tried to keep it as small as possible. The header is from Caterham UK and is different from some earlier photos of 4-1 headers in this post

 

I have yet to fit a muffler, I have a Magna Flow stainless muffler that will be fitted as a first attempt to make sound at Laguna which is 90db for my first track day with this new set up. I doubt that will be quiet enough so I plan to have a second system prepared with an oval muffler that will be used for Laguna only. Any tips on quieting a Cross Flow engine Seven much appreciated. Thanks for all your prior help and support. I will be at the GG Lotus Club track day 11/7

 

 

 

 

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Block: Ford OHV 2265E Kent AX Block

Bore: 84 mm Stroke: 77.62 mm

Capacity: 1721 cc

Compression

Ratio: 11.5:1

Maximum

Power: 160HP at 7,200 RPMs

Maximum

Torque: 125 ft/lbs at 5,600 RPM’s

Ignition Timing: 12 degrees B.T.D.C. at 1,200 RPMs

OR 34 degrees B.T.D.C. at 4,000 RPM's

Fuel: 110 Octane (Shell Purple)

Cylinder

Head: Gas Flowed with Enlarged Ports

Valves: Ivey, Oversize (Intake: 41mm, Exhaust: 35mm)

Valve

Springs: Ferrea (S10115) Heavy Duty, Duplex with

Burton Hardened Retainers

Camshaft: Kent A6

Rockers: Burton High Lift Roller Rockers (1.69-1)

Pistons: CP Carillo Forged 84mm bore 11.5:1 CR

Flywheel: Stock Lightened to 12lbs. and balanced

Con Rods: Stock Ford lightened and

Balanced 600 g (with bolt)

ARP Bolts

Crankshaft: SCAT SCCA Crankshaft

Clutch: Helix Cover

Helix 3 paddle clutch plate

Throw Out bearing (Burton)

Ignition: Distributor: Pertronix Flame Thrower

Coil: Pertronix Flame Thrower II

Lubrication: Titan 5 port Dry Sump Pump

Six Quart Alloy Oil Tank

Alloy Dry Sump Pan

Remote Oil Filter Housing

MOBIL 1 Oil Filter

Intake

Manifold Caterham Cast Alloy

Matched to head and carbs

Carburation: Twin Weber 45mm DCOE

Air Filters: Weber three screen filters

Header: Caterham Competition 4-1

Collector 2” Outlet

Stainless Steel

Muffler: Magnaflow

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