K8 Busa installation.
Discussion
Thanks gents. I already have the larger output coupler (have the HD shaft in my current motor) and getting the right nut is easy enough.
No MBE or paddle shift here. I'm over in Canada, and don't have to run the Radical ECU, so I don't (run the stock Suzuki ECU and wiring). What's the issue with the airbox?
Also, I had heard that the output shaft is offset slightly differently. Any issues there in terms of connecting it to the diff?
Thanks again.
-Matt
No MBE or paddle shift here. I'm over in Canada, and don't have to run the Radical ECU, so I don't (run the stock Suzuki ECU and wiring). What's the issue with the airbox?
Also, I had heard that the output shaft is offset slightly differently. Any issues there in terms of connecting it to the diff?
Thanks again.
-Matt
in that case matt life is much easier just replace the whole ecu and wiring from the k7 set up with all the new stuff from the k8. The holes for the base of the air box will be in the wrong place so you can either buy a new one or fibreglass up the old one and cut new holes.
unfortunately i had to ditch those superb twin injector throttle boddies and use jenvey but if you are using the new k8 ecu you will have no such problems. it goes without saying the old k7 ecu will not work with the new k8 engine due to the 8 injectors.
as you say the outputshaft is thicker so you will need a different drive cog. There are some issues with the 16mm gudgeon pins that is fitted to the k8 rather than the 18mm on the k7. I believe there are also some issues with the valves but you can speak to james at powertec about that i think they have a mod.
i can assure you the k8 is vastly superior i would love to have tried the 8 injector set up i bet it is superb.
unfortunately i had to ditch those superb twin injector throttle boddies and use jenvey but if you are using the new k8 ecu you will have no such problems. it goes without saying the old k7 ecu will not work with the new k8 engine due to the 8 injectors.
as you say the outputshaft is thicker so you will need a different drive cog. There are some issues with the 16mm gudgeon pins that is fitted to the k8 rather than the 18mm on the k7. I believe there are also some issues with the valves but you can speak to james at powertec about that i think they have a mod.
i can assure you the k8 is vastly superior i would love to have tried the 8 injector set up i bet it is superb.
Hi Matt
This is the technical department from Radical uk.
As far as converting the motor over from k7 to k8 goes, the engine mounts are the same, as is the engine cradle, and the headers.
The main differences, from a standard k7 radical set up are:
If using Jenvy throttle bodies, these are spaced differently, the actual body is the same though. This would mean you will also need a new injector rail.
As the injector bodies are spaced differently the air box holes from the k7 motor won't line up, although the shape of the air box itself is the same.
Powertec use a different sump system on the k8.
The coupling is different, and requires a new coupling in the drive unit.
Powertec also change the inlet and exhaust valves.
We only have a map for the k8 engine on our current ecu, which is life, and not mbe.
If you have any further queries then you can get in touch with us at technical@radicalsportscars.com
This is the technical department from Radical uk.
As far as converting the motor over from k7 to k8 goes, the engine mounts are the same, as is the engine cradle, and the headers.
The main differences, from a standard k7 radical set up are:
If using Jenvy throttle bodies, these are spaced differently, the actual body is the same though. This would mean you will also need a new injector rail.
As the injector bodies are spaced differently the air box holes from the k7 motor won't line up, although the shape of the air box itself is the same.
Powertec use a different sump system on the k8.
The coupling is different, and requires a new coupling in the drive unit.
Powertec also change the inlet and exhaust valves.
We only have a map for the k8 engine on our current ecu, which is life, and not mbe.
If you have any further queries then you can get in touch with us at technical@radicalsportscars.com
Thanks to Barry for taking time to chat with me on the phone. I also talked to PowerTec and got myself all sorted out.
Since I'm using the Suzuki ECU, throttle bodies and wiring harness, I'd have to swap over to the K8 versions of each of those (not a big deal, as it's all usually included with a car kit from eBay or similar).
According to both Barry and PowerTec the dry sump fittings swap over. They may be doing something new with the K8 motors in terms of dry sump, but it's merely an evolution of the entire system, not something K8 specific. PowerTec themselves confirmed that my existing dry sump setup would work.
In terms of physical installation, PowerTec confirmed that a different driver coupler and gear drive unit input shaft are required. It seems the K8 output shaft is larger than the K7, but not as large as the "heavy duty" output shaft fitted to some K7 engines. Also the spacing of the output shaft IS different, requiring a new input shaft for the gear drive unit.
Finally, all confirmed that the spacing of the throttle bodies is different on the K8, requiring either a new airbox or modification of the existing airbox.
Thanks once again to all who commented. If/when I decide to go ahead with it, I'll be sure to post my experience here on PH.
-Matt
Since I'm using the Suzuki ECU, throttle bodies and wiring harness, I'd have to swap over to the K8 versions of each of those (not a big deal, as it's all usually included with a car kit from eBay or similar).
According to both Barry and PowerTec the dry sump fittings swap over. They may be doing something new with the K8 motors in terms of dry sump, but it's merely an evolution of the entire system, not something K8 specific. PowerTec themselves confirmed that my existing dry sump setup would work.
In terms of physical installation, PowerTec confirmed that a different driver coupler and gear drive unit input shaft are required. It seems the K8 output shaft is larger than the K7, but not as large as the "heavy duty" output shaft fitted to some K7 engines. Also the spacing of the output shaft IS different, requiring a new input shaft for the gear drive unit.
Finally, all confirmed that the spacing of the throttle bodies is different on the K8, requiring either a new airbox or modification of the existing airbox.
Thanks once again to all who commented. If/when I decide to go ahead with it, I'll be sure to post my experience here on PH.
-Matt
you are very welcome matt did you get the info you need regarding the internal mods or do you still want me to email you? Mat is using everything standard on the suzuki ecu, throttle boddies etc so will require very little modification and should be an easy transplant no problems with the fuel rail etc because he is dumping the whole lot in intact. Apart from the normal internal mods, new drive cog for bigger diameter output shaft, and a different air box base he should be good to go, should be running by lunch time!!
you are very welcome matt did you get the info you need regarding the internal mods or do you still want me to email you? Mat is using everything standard on the suzuki ecu, throttle boddies etc so will require very little modification and should be an easy transplant no problems with the fuel rail etc because he is dumping the whole lot in intact. Apart from the normal internal mods, new drive cog for bigger diameter output shaft, and a different air box base he should be good to go, should be running by lunch time!!
Matt Graham said:
My employer requires me to carry a mobile phone, and in return, picks up the bill no questions asked. All in all, I think I was on the phone for about 15 minutes. 
That sounds like a rehearsal Matt! Was just wondering whether Bazzer had copped 'Missed Call, To Return The Call, Please Key 5' It'd be good if you could post up some pics when done ......... tomorrow lunchtime it is then.
All,
Bringing this topic back to the top. I've started down the road of the K8 installation in the SR3. From what I can tell PowerTec no longer fit a head drain to the K8 busa as they did to the K7. I like the looks of that!! Can someone confirm the no head drain?
Thanks!
Pictures to follow shortly. Should have the engine in the car next weekend.
-Matt
Bringing this topic back to the top. I've started down the road of the K8 installation in the SR3. From what I can tell PowerTec no longer fit a head drain to the K8 busa as they did to the K7. I like the looks of that!! Can someone confirm the no head drain?
Thanks!
Pictures to follow shortly. Should have the engine in the car next weekend.
-Matt
Update:
I'm happy to report that all of the dry sump fittings from the K7 engine went on to the K8 as expected, without a hitch. Had to purchase a 36mm socket to fit the K8 countershaft nut, and then found the socket I purchased was too big (outer diameter) to fit inside the coupler. Luckily I was able to put the WWI era lathe my Grandfather gave me to good use and turn the socket down just enough to fit.
That, however, led to the next issue: The countershaft on the K8 is a hair longer than the K7, and with the K8 specific coupler spaced back just a bit, the end of the countershaft sticks out just beyond the end of the coupler. Not being sure whether this would foul the coupler on the gear drive unit, I called it a night and will call Radical in the morning to confirm the fitment.
Hope all of this is helpful to someone else someday.
-Matt
I'm happy to report that all of the dry sump fittings from the K7 engine went on to the K8 as expected, without a hitch. Had to purchase a 36mm socket to fit the K8 countershaft nut, and then found the socket I purchased was too big (outer diameter) to fit inside the coupler. Luckily I was able to put the WWI era lathe my Grandfather gave me to good use and turn the socket down just enough to fit.
That, however, led to the next issue: The countershaft on the K8 is a hair longer than the K7, and with the K8 specific coupler spaced back just a bit, the end of the countershaft sticks out just beyond the end of the coupler. Not being sure whether this would foul the coupler on the gear drive unit, I called it a night and will call Radical in the morning to confirm the fitment.
Hope all of this is helpful to someone else someday.
-Matt
Matt Graham said:
Luckily I was able to put the WWI era lathe my Grandfather gave me to good use and turn the socket down just enough to fit.
Great thread Matt ........ keenly waiting for the next episode, good to wake up to something interesting that's come in overnight - finally, an advantage of time zones!Good on Grandpa too - another bit of ancient kit that was so well made and over-engineered that it's still doing it's stuff donkey's years later - I've got a lovely Dunlop footpump made of a cast iron frame and brass piston, probably about 1930-ish, that is still keen, willing and able to pump air into the Rad's tyres! Long gone are the days when stuff was that inherently well-made (and indeed repairable). Better leave it at that, else I'll be off on one again on the multitude of utter crap we get sold today, whereupon I'll be moving remorsely on to 'used to be Hong Kong, then it was Taiwan and now it's China ............' !!!!!!!!!!!!!!!!
Glad to see someone is reading this other than myself.
With respect to the coupler, I had originally been told by a few sources that I needed a new engine coupler and gear drive unit (GDU) coupler. When I ordered the parts from Radical I was told the engine side coupler is now universal and could be used with the existing GDU coupler. Turns out I have a particularly old GDU coupler, so apparently I DO need both couplers. The one I need looks like this:
Anyway, nothing that a call to Radical and a few more $$$ won't solve.
So it will be a few more days before the engine goes in.
-Matt
With respect to the coupler, I had originally been told by a few sources that I needed a new engine coupler and gear drive unit (GDU) coupler. When I ordered the parts from Radical I was told the engine side coupler is now universal and could be used with the existing GDU coupler. Turns out I have a particularly old GDU coupler, so apparently I DO need both couplers. The one I need looks like this:
Anyway, nothing that a call to Radical and a few more $$$ won't solve.
So it will be a few more days before the engine goes in.
-Matt
Far too long since I updated this thread.
After getting the correct gear drive unit coupler from Radical, the engine went in, physically, without a hitch.
As I had posted previously, I'm using the Suzuki electronics, and once I got the wiring harness back from the folks doing the modifications for use in the car, I had a few simple connections to make (kill switch, ignition switch, battery, fuel pump, etc).
Had to modify the airbox with a small piece of sheet aluminum. The spacing on the throttle bodies is different for the K8 compared to the K7 engines. This job was a little fiddly, but it was worth doing over ordering a whole new airbox from Radical.
Plumbing wise, the water and oil plumbing connected as expected. As I stated earlier, Radical no longer do a head drain on the K8, so I had an extra port on the oil pan. I simply purchased a -10 cap for the unused port. Everything else connected just as it should. The newer pump/pan that Radical is now using is functionally the same as the current pump/pan, but a little more clever and requires fewer external oil lines. Radical have also switched to having the scavenge pump push the oil through the cooler and then into the dry sump tank, rather than using the oil cooler ports on the engine. Since my lines/fitting sizes were setup to use the oil cooler ports on the engine, I chose to do this the "old" way. I may update it next off season, as the plumbing is a little simpler. I does require the removal of an engine oil galley plug in the engine to work the 'new' way.
To plumb the fuel I simply got an adjustable fuel pressure regulator, and a fitting for the stock fuel rail from Peter D. Motorsports in Arizona, USA. This basically allows a -6 fitting to feed the stock fuel rail. Pretty inexpensive, and easy as pie.
The header and exhaust bolted right up as expected, no dramas.
When I attempted to start the motor the first time, it would turn over, almost catch, and then not run. Found out that the K8 throttle bodies have an Idle Speed Circuit which closes the butterflies fully and allows air through via a separate tube (which I had plugged per instructions from the wiring harness modification folks). All I had to do was turn up the old fashioned idle screw a little and the engine caught and idled like a champ.
Took the car to the dyno before the first test outing and the car ran well. HP readings were over 200HP at the rear wheels, so I'm pretty sure the dyno is reading VERY high. There is no way my stock 1340cc K8 is putting out that kind of wheel hp.
One test and two race meetings on the car, and so far the engine is running great (oil and water temps stay well in check, and the car pulls well and show good speed compared to the K7). Sadly, our weekends have been cut short by the diff issue I posted about earlier.
I'll be sure to give a full season review once the diff gets sorted.
-Matt
After getting the correct gear drive unit coupler from Radical, the engine went in, physically, without a hitch.
As I had posted previously, I'm using the Suzuki electronics, and once I got the wiring harness back from the folks doing the modifications for use in the car, I had a few simple connections to make (kill switch, ignition switch, battery, fuel pump, etc).
Had to modify the airbox with a small piece of sheet aluminum. The spacing on the throttle bodies is different for the K8 compared to the K7 engines. This job was a little fiddly, but it was worth doing over ordering a whole new airbox from Radical.
Plumbing wise, the water and oil plumbing connected as expected. As I stated earlier, Radical no longer do a head drain on the K8, so I had an extra port on the oil pan. I simply purchased a -10 cap for the unused port. Everything else connected just as it should. The newer pump/pan that Radical is now using is functionally the same as the current pump/pan, but a little more clever and requires fewer external oil lines. Radical have also switched to having the scavenge pump push the oil through the cooler and then into the dry sump tank, rather than using the oil cooler ports on the engine. Since my lines/fitting sizes were setup to use the oil cooler ports on the engine, I chose to do this the "old" way. I may update it next off season, as the plumbing is a little simpler. I does require the removal of an engine oil galley plug in the engine to work the 'new' way.
To plumb the fuel I simply got an adjustable fuel pressure regulator, and a fitting for the stock fuel rail from Peter D. Motorsports in Arizona, USA. This basically allows a -6 fitting to feed the stock fuel rail. Pretty inexpensive, and easy as pie.
The header and exhaust bolted right up as expected, no dramas.
When I attempted to start the motor the first time, it would turn over, almost catch, and then not run. Found out that the K8 throttle bodies have an Idle Speed Circuit which closes the butterflies fully and allows air through via a separate tube (which I had plugged per instructions from the wiring harness modification folks). All I had to do was turn up the old fashioned idle screw a little and the engine caught and idled like a champ.
Took the car to the dyno before the first test outing and the car ran well. HP readings were over 200HP at the rear wheels, so I'm pretty sure the dyno is reading VERY high. There is no way my stock 1340cc K8 is putting out that kind of wheel hp.
One test and two race meetings on the car, and so far the engine is running great (oil and water temps stay well in check, and the car pulls well and show good speed compared to the K7). Sadly, our weekends have been cut short by the diff issue I posted about earlier.
I'll be sure to give a full season review once the diff gets sorted.
-Matt
Updating again as my season has pretty much wound down now.
The update of my older chassis (#0088) to K8 engine was an unqualified success.
Oil pressure, oil temps and water temps were bang on all season. I continuously checked the data after every session, looking for any sign of the "K7" fitment kit not working on the K8, and I could find none.
The modified Suzuki K8 electronics and fuel injection performed flawlessly as well. I purchased a programming cable and downloaded some software that allow me to tune the stock Suzuki ECU, thus eliminating the need for any extra stuff (i.e. Power Commander) and kept the wiring simple.
I was able to pick up another very low miles (under 1000) spare K8 engine (including throttle bodies, wiring, ecu, etc) for a great price. Plan is to keep the engine stock (most of the other local SR3 owners are sticking with 1300/1340 engines, so we all just run together) and leave it in there for at least another 20-30 hours.
Anyone looking to make the conversion to K8 power, feel free to fire any questions my way.
-Matt
The update of my older chassis (#0088) to K8 engine was an unqualified success.
Oil pressure, oil temps and water temps were bang on all season. I continuously checked the data after every session, looking for any sign of the "K7" fitment kit not working on the K8, and I could find none.
The modified Suzuki K8 electronics and fuel injection performed flawlessly as well. I purchased a programming cable and downloaded some software that allow me to tune the stock Suzuki ECU, thus eliminating the need for any extra stuff (i.e. Power Commander) and kept the wiring simple.
I was able to pick up another very low miles (under 1000) spare K8 engine (including throttle bodies, wiring, ecu, etc) for a great price. Plan is to keep the engine stock (most of the other local SR3 owners are sticking with 1300/1340 engines, so we all just run together) and leave it in there for at least another 20-30 hours.
Anyone looking to make the conversion to K8 power, feel free to fire any questions my way.
-Matt
Gassing Station | Radical | Top of Page | What's New | My Stuff