Formula Atlantic 4A-GE turbo conversion

[Chris Wilson]

Thought I'd post up my work so far on converting a Formula Atlantic race 4A-GE to forced induction. I will copy / paste form another forum to get up to date, as this is a work in (slow...) progress It may scan a bit strangely at first as i will miss out the odd reply from the other forum. Shared experiences with big power circuit race turbo 4A-GE engines very welcome, thanks.

[Chris Wilson]

Anyway, this is the car in its present form, externally I expect that very little will change. probably just the deletion of the air box, which interferes with the back wing air flow anyway. I may will draw cold air from a filter in one of the side pods and blank off the rear body opening for the air box.

[Chris Wilson]

Here are some pics of the bay as was, and now stripped of stock headers and exhaust pipe, and stripped of the twin 48DCOE Webers.

http://www.gatesgarth.com/4age/4age.html

Jenvey here in the UK will supply some very short throttle bodies and the injector rail, as well as one of their new turbo plenums that bolts right up to their bodies. There's a slight chance i will use spacers and a single throttle body, but the better response of individual ones is tempting, despite the added cost.

[Chris Wilson]

Had to make decision today on what turbo to use, I asked my tame turbo expert, and he said a Garrett GT3071R with a .64 A/R would be a good start point, and Turbo Dynamics and Owen Developments concurred, so I have ordered one of these to do initial trials with. Turbo Dynamics are shipping a bare turbo to the fabricators to arrive tomorrow. The T28 footprint helps a lot, as the installation is very tight (see IrfanView HTML-Thumbnails if interested, but not updated from earlier). I took the car down to Thame this morning and Primary Designs are making and fitting an Inconel manifold, the support bracketry for the turbo, and a silenced exhaust system, all thermally coated in Zircotec. I have used Primary Designs for an F3 system, and for some prototype work before, and can't speak highly enough of this company. They now take on some general motor sport fabrication work, too, so there's less to-ing a fro-ing than there used to be, as they can fabricate ancillary stuff in house. I justify their high prices by telling myself 60% of the F1 grid can't be wrong in using them The guys there are a genuinely enthusiastic and helpful bunch who happily share a wealth of knowledge gleaned at the highest levels. They were making a new Arrows BMW Megatron turbo manifold, for an historic F1 car, and it was truly a work of art, more deserving of the Tate Modern than any exhibit I have yet seen on the TV They should have a gallery on their web site, some of things they make are very deserving of photographic record. I can't understand why they haven't...

http://www.primarydesigns.co.uk is their place.

I am initially committed to this turbo now, so we'll see how it goes.

I have decided to struggle and remake the rear bodywork to accommodate and air to air I/C.

I may well run some cams with less duration when I have the engine out for the low compression pistons and refresh. The data logging in the new Motec ECU will accommodate the 4 K type thermocouples that were in the original N/A manifold, so I am having bosses welded in the turbo manifold primaries to log the EGT's on each cylinder, which should be handy. It was a bit OTT on an N/A engine, but I didn't pay for them, and their amplifiers, they came with the cars digi dash.

[Chris Wilson]

Primary Designs reckon it may be done by the end of this week, so should be picking it up at the weekend or early next week. I have sent some stranger a 50 quid deposit by Paypal on a 4-AGZE engine (that's the supercharged one, the block has oil squirters for cooling pistons. He hasn't acknowledged the deposit, and his mobile now has a message that he's having trouble with voice mail, and to either try again later or send a text. My antennae are quivering.... Still, if he comes good I can build the engine on another block and leave the Atlantic one untouched in case this all turns to sand. I'll also have a spare late head and a supercharger and manifolding to sell to MR2 people.

Pat at Primary has promised some photos of the manifold in bare Inconel, before it's sent for ceramic coating, I'll post them up.

I have decided that some softer cams are a good idea, so will search out possibilities next. Need to re install a charging system, do a wiring loom for injectors and ancillary sensors, and fit the Motec. Need to make a fuel swirl pot and high pressure fuel system. need to buy throttle bodies, fuel rail and injectors, and buy / make a Plenum. Jenvey are bringing out a cast alloy plenum for their bodies, but it's now been put back to next year, I may have to get something fabricated, which could be costly

I also need to source an air filter for the turbo, have an intercooler made and make mounts for it, and, (bodywork which I hate...), make moulds to have an air scoop produced to feed the I/C.

[Chris Wilson]

Collected the car today, some photos of the Inconel manifold and dummy turbo, wastegate collector and exhaust system, before it gets ceramic coated at:

http://www.gatesgarth.com/4age/primary/primary.html

[Chris Wilson]

Thought I'd copy paste some of the downsides, issues and problems with this project, as well as glitzy pics and the big HP numbers

I posted this on another forum, and i have also had issues with the new manifold / exhaust system, which is having to be resolved.

Charging the battery:

Is anyone aware of any tech info on how fast an alternator needs to be driven to give a worthwhile charge rate? I am looking at driving a small modern, lightweight alternator off a Hewland FTR inner tripod joint, by turning and welding on a bell shaped toothed wheel. I see some photos of Group C cars using such a system, but it's far from clear what sort of pulley sizes are involved. Thanks.

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My concern is this car (a Zeus Supersports car, a bit like a radical in appearance, with a Toyota 4-age engine) was run on carbs, with a Red Top pump, and just a very basic Electromotive ignition only managaement. For endurance races someone fitted a small car alternator (Japanese one, from some tiny import car, like Brise sell). They decided to drive it from a longer cam belt, but the mounting of the alternator wasn't brilliantly executed and I lived in fear of it moving and the cam belt failing or coming off. It also suffered failures due to harmonics breaking internal wires. No I am turbo charging the engine and fitting full fuel injection. I am told, and have seen, that modern FI, Motec in my case, doesn't like wild voltage changes, although it does allow for injector pulse width trimming over contained voltage changes. I think I am going to need a charging system. I have recently run the N/A engine on carbs with no alternator and a stock cam belt system, and felt happier. It would run a full track day with just a quick trickle charge into the Varley Red Top 30 battery during lunch, from a 10 amp charger. Once modified to pressure charging the turbo will be very near the only place to mount an engine driven alternator, so this is why I now look at running one off the driveshaft. It moves it away from heat, allows unadulterated cam belt routing, and should dampen the worst harmonics, indeed, without cam belt tension to worry about, it could be isolated on rubber bushed mounts. I think I'll risk it and maybe aim for a 3 to 1 geared up drive? Thanks

[Chris Wilson]

Not much progress of late, due to work commitments and waiting for the turbo to be built and sent. I also had a slight issue with the collector for the wastegate in the new exhaust. The turbo people sent a dummy turbo to primary Designs, but didn't tell them it had been bored out in the exducer area of the turbine housing. Primary made a beautifully crafted stub to enter this bored out region, unknowing that the real turbo had a smaller bore here. They kindly modified the housing to fit the "real" turbo.

The turbo and amended pipework are now with me, and I am now pursuing some custom pistons for the engine. I have decided against multiple throttle bodies and going for a single 60 mm or so body on the end of a custom plenum. This makes mapping easier and should pull torque up a bit. It's also cheaper, too

Hopefully I can make a bit more progress now.

[Chris Wilson]

Done nothing but pay out the last few days. Siemens Pico style 650 cc / min disc type injectors, Bosch Motorsport FPR, Bosch 044 fuel pump, custom plenum (£1200 with fuel rail), Marelli fast reaction air temp sensor, Bosch Hall effect cam position sensor, Marelli crank position sensor, £800 quid on Aeroquip and fittings, £400 on billet main caps, blah blah. Hope this idea works... Need cams and pistons still, an engine gasket set, machining work on the used block I have, an ecu. God, it's frightening, and I have the Skyline engine still eating money, although that's nearly done and should be on a dyno in the early New Year. It's projects like this that mean I never spend more than 50 quid on a TV, and never buy the exotic latest gizmos like fancy mobile phones, and all those funny boxes of electrickery people litter their houses with that the newspapers would have you believe you cannot live without

[Chris Wilson]

Been a bit waylaid with building 2 Skyline engines, so this has taken a back seat, but a custom plenum is in build, and Jenvey are sending me a 65 mm throttle body, some injector tubes, a fuel rail and fittings. i am going single body, mainly for cost and ease of mapping. Space precluded full size injectors without a lot of messing, so today some Siemens "Pico" style injectors arrived, which really are tiny. They flow about 670 cc / min at 3 bar pressure, and will go to about 940 cc / min at 6 bar, sp plenty of headroom there. I have also got the crank trigger sorted, and am weighing up the options for a cam position sensor location. I have a Bosch Motorsport 044 fuel pump, and a Bosch Motorsport fuel pressure regulator here now, too. Once the plenum is dummied up I can pull the engine and strip it, and get pistons ordered (they'll have to be specials) and some cams sorted out. I will almost certainly build it based on a used 4A-GZE block with oil squirters I have bought, and will fit it with billet main caps and line bore it. Even in N/A Atlantic spec the stock caps are known to move about a bit!

Finally, i have made an oil drain adaptor for the turbo, and sourced the correct banjos and banjo bolts, and the Aeroquip hoses to take water to and from the turbo cassette, and to feed it with oil. I have also made a restrictor to limit the oil volume to the turbo, as it's a ball bearing one, and they don't like a lot of oil flow.

A Siemens injectors is shown below, neat huh? Especially for something that will idle to emissions standards on a road engine, yet flow nigh on 1000 cc / min if required. The joy of disc valve injectors Specs at http://www.mmcompsys.com/download_zo...20injector.pdf

[Chris Wilson]

More progress, the plenum is done, it's been a nightmare and very time consuming, and as such, costly, but it's pukka with fully radiused bellmouths inside, flow bench tested, made of heavy walled spun alloy with a turned alloy trumpet shaped inlet pipe. Jenvey supplied the 65 mm throttle body and the fuel rail. The original Weber carb manifold was modded to take injector bosses and the fuel rail mounting posts. Just dummied it up on the engine, seems fine thank God. Tommorow I ensure the measurements I took were accurate and the rear bodywork clears everything.....The whole caboodle was powder coated in crinkle black.

Once the bodywork clearance is verified it's engine out and full strip time, and order the pistons and cams, sort the turbo drain, and prepare the block I am going to use one with piston oil squirters. It's having billet steel main caps to add a bit more bottom end strength.

http://www.chriswilson.tv/plenum/plenum.html

[Chris Wilson]

I managed to strip the bulk of the engine today, now that I know I have plenum clearance and have 3 confirmed options for intercooling the thing. The only two problems I found were erosion of the Titanium Nitrate coating on a couple of tappet buckets. I COULD get them re coated, but the people that do it are slow, and don't like little batches, so I will just buy a few more buckets ready done from the USA. The other problem only came to light when I removed the crank, which is fully polished and really should be on our lounge table, rather than inside an old Toyota 4 pot! The Yanks love BS and certainly had someone's trousers down polishing this thing, it looks chromed. This engine had run perfectly, with perfect oil pressure and no apparent issues, and as you can see from the photos below all the main caps LOOKED perfect, but on undoing the (ARP) bolts on number 2 main journal the cap fell into 2 pieces I am intending to fit steel billet main caps anyway, and won't be using this block in the turbo build, so it's no big deal, but I was surprised how well a 10,000 RPM + engine had held together with only 4 fully functioning main caps....

I have decided to buy yet more rods, and have pistons with 20 mm pins made at 8.75 to 1 compression ratio. I will also run 3/8 inch rod bolts, rather than the very small, and expensive high spec 5/16 bolts in the current Carrillos. The turbo pistons may well be a bit heavier due to thicker crowns and thicker rings (I will go up from the current 1mm rings to 1.2 mm ones). So now it's time to get the 4A-GZE block cleaned, honed to round and parallel on the biggest current bore, some billet main caps fitted, line bored and honed, the head deck ground, and some custom pistons ordered from CP or JE. I can also spec and order the new rods, too. Finally I need to order the cams, which will almost certainly end up being a custom grind on billets. This is the part of the project I really enjoy, as things start to come together a bit. It's a good job I did decide on pursuing this project, if I'd been tempted to run it in N/A format any longer I suspect the bottom end would have let go

Photos of a genuine, and slightly broken, Formula Atlantic spec 4A-GE engine in bits at http://www.newbury-house.com/atlantic/atlantic.html

Cheers.

[Chris Wilson]

Got some billet mains caps from the USA, and they are just good for paperweights or bits of steel to make something else out of. They turned out to have come off engines that had ALREADY been line bored and honed and on my 2 blocks they are out by 5 thou, in a negative direction, hence scrap. Not happy... Rather than *iss about any more I am having CAD drawings done and having 3 sets of caps machined up over here, so i can use 2 sets and have a spare set to sell or whatever. I also have to pay 500 quid towards a fixture to machine them and the correct hone for the guys Sunnen machine. It's been a nightmare finding someone to do this line boring and honing CORRECTLY, most places ain't got a clue. If you're thinking of having caps on a 2JZ-GTE let me know, my man has the 2JZ fixture for his CNC machine and access to proper caps that fit his fixture, but none of this sort of stuff is cheap.

The digital piston rendering is done and JE are making pistons, and Carillo are making custom rods. Perfect Circle are making the ring packs. I have decided to get 2 sets of pistons made, so I have a spare, plus 3 sets of rings. Spending a bit more now is a lot cheaper than ordering in single sets later.

Whilst waiting the five or weeks for the above I am looking at getting the intercooler made. I have made a swirl pot for it, as the commercially available ones were too tall for where I want it to go, and the pipe fittings came out in the wrong places.

[Chris Wilson]

Right, these things take time Collected 3 freshly bored, decked and honed blocks all with custom billet cams made and fitted and honed to size. All within 3/10 thou inch to size and roundness. Crank is being ground on the mains as there was 1.5 thou "bend" in it, but it's in such a bizarre place I suspect it was made like that from new. Carillo rods are made and here, as are the special forged pistons and the ring packs. Once the crank is here next week I can do a dry build, and get the head gasket made up. Kent sent the cams about 3 weeks ago, and they will need the shimming doing. So at LONG last the engine can go together soon

[Chris Wilson]

OK, managed to get some work done on this project this morning. I checked all the caps for bore size, ovality and straightness, with a Mercer gauge and a machined bore guage bar. As I expected and hoped, they were spot on. Dry built with the steel crank in the mains, and checked actual bearing clearances again, with Plastigauge. Was wanting 1.5 thou inch (0.0015") and I think you must agree, we have got pretty much what we were after Will fit a new piston to one of the new rods and check deck heights after lunch, so i can get a head gasket made to give the CR I am after. That should finalise the engine bits, save for valve springs and 2 missing shims for under the springs. I hope to have the block built this week.

http://www.chriswilson.tv/4agecrank/4agecrank.html

As an aside I decided to have the caps made with little crescent shaped cut outs in their sides, to allow a tool to engage to lever them from the block rails, as these can be fiddly to remove otherwise. They work well. I'll do future ones the same I think

We now have CNC files, tooling and some actual blanks for 2JZ-GTE steel main caps. Be aware though, that with *PROPER* machining this mod isn't cheap, but witness the 2JZ engines which have had steel caps fitted that have given catastrophic trouble, due to them not having been done correctly.