GT74 High Compression Six Speed

Keep going with the current ones till you hit spark blow out...then re-gap them down in stages to a min of 0.65mm....that should get you almost there I'd have thought.

Dont regap after they have been through a heat cycle though.

2 sets of coppers never lasted 2 min in my car while mapping at 1.5bar,couple boost runs and they was f**ked, (plus we was getting knock with the coppers at 1.5bar, put Iridiums at the same boost no knock:search:) Mapped both my supra's on R7436-9 NGK and never a problem with them, pricey though at £150 a set

It is true and even with Jamie's ignition system being direct fire and having a DLI lol

The coppers just were not igniting all the mixture and caused uncontrolled burns which equalled Det.

See i have been turned now and prefer customers to use BKR8EIX plugs. Have mapped 100's of cars on them and none have broke tips, caused any ignition issues etc

Some of these also in the drag cars i have done have seen serious knocking event due to fuel starvations and still survived.

Denso's on the other hand, walk away

Ryan

Dont regap after they have been through a heat cycle though.

Not a chance.

Interesting Ryan, I wonder why the coppers would not ignite all the mixture, yet Iridums would?

Probably something like the coppers getting hot and the resistance rocketing up, stopping the spark from happening.

-Ian

Interesting reading on the spark plugs. I personally would not touch Densos because of what I have read and what I have witnessed with those plugs... kind of put me off Iridiums really especially given their expense compared with a set of coppers.

Currently running BKR7E gapped at 0.8mm after a previous set started misfiring (just the odd miss) with advanced ignition timing on race fuel - those were gapped at 0.9mm and were fine like that on pump fuel, BPU+ and c1.1bar boost. Do we think BKR7EIX would be more resistant to the aggressive race fuel mapping abuse? What about the standard gap they come with, is it not 1.1mm? Are people finding standard gap on them isn't an issue because they're iridium and the spark manages to jump the larger gap just fine with raised boost pressures?

Cheers,

Brian.

I'm using BCPR7ES in my supra with 0.7 gap. With gt4094r @1.6bar they were fine after 3000miles and still going strong. This includes the mapping also (pump gas). No misfire whatsoever. However, I'm using M&W pro16 ignition and direct fire which obviously helps a lot.

I was getting bored in a traffic jam on a motorway this afternoon so let a bit of a gap build up, then tested the clutch;). Thought nothing of it, about ten minutes later, as the traffic opened up I launched it and pulled in to the out side lane to over take a car and pulled back into the inside lane, like you are supposed to do, (as I don't own a BMW). The car in the out side lane flashes to let me out as I signal to over take the next car, then pulled in again. The same car then flashed me for the next couple of overs take I did. The traffic slows, the same guy who kept flashing pulled along side, giving me the big thumbs, and gesturing that I should pull another over take. Of course only too happy to oblige. The traffic crawls to a halt , the guy pulls along side,and shouts "That thing pull's like fk" we end up chatting for a while, turns out his neighbour has a MKIV, has owned it for years but never uses it and has kept it in his garage. Sounded like a little purchase opportunity. Unfortunately the traffic opened up and I did not get the chance to find out more about the unused MKIV.

This is the first time I have ever had anyone pay such a compliment, about time though, as it does pull like fk and sounds awesome.

Just to make the afternoon even better, whilst taking a scenic route to avoid the Friday jams, I headed along a straight at around 55mph really officer. A car, some distance ahead, in a right hand side junction pulls out ahead perfectly safely. I saw the bonnet of a police car, move forward, in the same junction, so I took a precautionary glance at the speedo, still doing 55. The Police estate stopped so I assumed he had seen me as the road was dead straight. Suddenly he pulled out, so I hit the brakes and even with ABS, manged to get quite a chirp out of the fronts, the copper had a moments hesitation, then launched it to get away. I followed at a safe distance until the next junction. I pulled up behind him and had a very satisfying:yahoo: eye ball to eye ball in his rear view mirror. I could see from his eyes he knew he had messed up, but guess who would have got the blame, had I clipped him.

Sorry Phil, just checked the copper plugs i have. They are BCR8ES. They are the same as the BKR7E plug in size.

Thanks for looking.

Just a quick update about a product that may be of interest to many. I was beginning to get fed up with having inaccurate Speedo reading, every time I swapped tires. I also want to be able to swap diffs for the performance and economy benefits this can bring. I had got so used to Speedo readings being unreliable so was always relying on GPS. But having to use GPS just to drive in the local area is daft. Thanks to Martin I have a great little product that makes any alteration to the car that affects Speedo accuracy, easy to corrected very quickly.

The clip below also shows a neat little max speed recall feature. The example shown was recorded on a track and played back at home, sorry no sweet exhaust notes this time.

Hi Phil. What's this product called?

That's some acceleration Phil

Fantastic thread. Just read from start to here.

Great progress...Great car...

Fantastic thread. Just read from start to here.

Great progress...Great car...

lol - me too, subscribed now and awaiting updates.

I know who I'll be calling when I win the lottery...

LOL Nic, I wish.

The product is called Speedohealer V4. It is the latest version of a very small light weight resin sealed speedo corrector made for the bike market. I could not believe how small it is.

As it is made for bikes there are various looms to choose from. You need the generic loom. Soldering it in did not take long.

I'll add a couple of pics of the little control box in my car.

It is very simple to set up, and can carry two different setting at the same time. So you could set up road and track wheels. Drive to the track, pop on your slicks, press a button and your speedo is accurate. It is designed to cope with all sorts of sprocket arrangements on bikes, so has all we could ever need within its range.

To set it up you check you speedo against GPS, there even a little wire jumper, so you can do this when ever you need to. Find a smooth level bit of road hold 60 on your speedo and note the GPS(actual speed). You then work out the percentage error, there is even a calculator on the website. Enter the appropriate figure using a combination of button presses and that is it your speedo is healed!!!

I'll try and find which supplier I got it from, their delivery was amazing, paid at 14.00, delivered 09.30 the next morning. It might worth be seeing if a group buy might achieve an even lower price than the one I paid.

There is only one slight problem which is nothing to do with the speed healer, that I discovered last night. I had Road Angel and my GPS on at the same time and they indicated two speeds two mph apart. I want to check both against different GPS systems to see what speeds others indicate.

I have just contacted the guy I got my Speedohealerv4 from to see if he would entertain a group buy and beat the ebay price of £59.99. I will contact mods if he wishes to participate. If approved by mods I will start a group buy thread.

These pics show the size of the unit and the little button that is used to activate and cancel the maximum speed held in the memory. I have not got round to sorting out a switch yet but I will be mounting one on the dash somewhere. There is a good size coil of wire on the leads so lots of flexibility for mounting positions. The main unit is not one you have on disply, so mine will be staying in the passenger side behind the tunnel carpet.

This unit is ideal if you swap wheels or tyre sizes frequently, or if you do any other mods, ie mine swapping diff to utilise different final drive ratios, which put the speedo accuracy beyond acceptable. It will correct any errors between your actual speed and your indicated speed. It also acts as a maximum speed recorder, and will hold your maximum speed in it's memory and show it every time you press the indicate speed button. This figure can be cancelled at any time by holding the button down for more than two seconds.

I have finally got the dials to match the potential of the engine. I purchased a TRD 320KMH speedo to put in place of my standard 180 MPH unit. I used the Speedohealer to set it up to indicate MPH, this took about ten minutes using the value calculated on the Haltec website and then adjusting by a few tenths of a percent to get it spot on. I decided to blank out the silly 240 plus KMH, now MPH numbers, I think it looks about right now. According to the last test track run the TRD speedo is accurate to 1 mph at 100 mph and spot on at 30, 40 and 60 when measured against GPS at a steady speed. All I need now is a reasonable sizes MPH sticker to finish it off.

Nicely done.

It will look even better when what I plan to use to cover up the higher numbers is in place.

I had the first hiccup of the build last night. Got a really bad but intermittent misfire. This is what I found when I took the coil leads off.

Fortunately I had a spare.

I have had a number of enquiries regarding the sourcing and fitting of my throttle cable. As I did not buy an off the shelf kit, I had to source my own throttle cable. To do this I used my old stock throttle cable and a tape measure to work out the minimum length I would need. I then spent about an hour hunting round my favourite breakers for something suitable. Unfortunately nothing came close to what I wanted, so I ended up with a very long cable from a Nissan, I think, but am not 100% sure, it was a single point injection Primera.

This shot shows the cable leaving the bulk head. I am not sure if the number shown on the cable is a part number or not.

The cable sweeps in a gentle curve under my larger catch tank and round under the end of the brake master cylinder.

The cable feeds under the clutch master cylinder. I used the original throttle cable bracket to keep the cable away from the turbo hot side.

We used the spare clips in the brake line brackets to carry the cable across the bulkhead behind the engine. I think it looks very tidy.

The cable drops back into the bay over the top of the heater matrix feeds and on to the plenum.

The cable then runs under the fuel rail emerging just behind the throttle bracket.

The cable finishes its run at the Q45 throttle body. I think the route worked out well, much better than having a cable in the stock, over the engine position. The peddle action and return feels like stock. In the end, I think the choice of cable was perfect.

I am currently running BKR8EIX plugs, since reading Ryan's very helpful comments earlier in this thread. Since putting them in, the cold start map needs a tweak as they seem to need more air in the mix when the engine is cold. These plugs will probably be fine for boost up to 1.2 bar which is 60% more boost than I am running now.

Having a compression ratio of 9.5:1 we have so far done well to keep cylinder temperatures down and stayed free of detonation. I want to take what ever steps I can to remove items from the combustion chamber that might contribute to detonation, when we start pushing top end pressures. In race engines, spark plugs that have the ground electrode projecting into the chamber are often avoided, which reduces the likelihood of the tip of the plug getting too hot and becoming a potential source of det. These plugs sound ideal for my engine design and high boost levels.

Some of these designs keep the tip out of the chamber and within the spark plug opening threaded area.

If anyone has any educated input on pros and cons of each end type of plug, please let me know.

I am looking at these options:-

R7117 - heat range from 7 to 11 - Platinum

R7119 - heat range from 7 to 11 - Platinum

R7279 - heat range 10 only - Iridium

R6601 - heat range from 8 to 11 - Nickel Alloy

Would any of the above in a heat grade of 7 or 8 be suitable for the road, given my setup? Any suggestions welcomed.

Just a quick update

Martin mapped the car further up the boost range last weekend. The car now hits 1.15bar. Martin took off some fuel and timing lower down the boost range too. The car certainly feels much stronger lower down. The wheels are spinning up much more now. It may be time to add some traction control and get Race logic wired back in now.

No pics or vids as the test track was a bit busy. Had a little tunnel action alongside new Corvette C6. The Vette sounded very nice until I dropped the car into second and held 8000 rpm. A guy in a transit was obviously enjoying the show as he kept flashing so we could get the cars in an empty section of the tunnel and get a few rpm going. The car sounds like the Jun Supra.

http://uk.youtube.com/watch?v=b3dLh8GvPkI&feature=related

Having looked into the possibility of race plugs and discussed it with Martin, the short nose plugs may not be a good idea in my car. I have a set of iridum 8's in at the moment, they seem fine at 1.1 bar but at idle and startup the car is much lumpier, compared to when it was running copper 7's going to try a set of iridum 7's.

Termy

forgive my laziness for not checking through this thread but would a good water/methanol system not be ideal on your car running the higher compression ratio