[mikeinva]

thanks papa weeley
if you pause the video at 5:27 and look at the torque curve you'll see how strong the power delivery feels, it makes 50 lb/ft at 2500rpm rising to 60 lb/ft+ at 4000rpm then holding that to 7500rpm (basically it pulls just a hard whatever the rpm).
i think there is alot more to come when i fit the daytona 42mm throttle bodies

what size motor is that if its a 865 you need to find another dyno shop.

 

[mike-tt special]

sorry mike i thought everyone would realise it's 904cc.

yeh! those numbers from an 865 with 790 inlet cam and standard t b's would be crazy

correct me if i'm wrong mike(i'm sure you will lol) but looking at yours and others dyno graphs i don't think a 904 with 790 inlet cam,gasflow,2mm valves,36mm tb's and the D&D 2-1 would make more hp peak.also i would expect the same motor with the d&d 2-1 would have a big hole in the torque below 5000rpm.

 

[mikeinva]

well yes they will yours is in din hp so you dont have as much if it was in sae hp i think yours would be around 83 hp sae .But thats not bad.What i find hard to buy is 50 ft/lbs at 2500 no 904 can even do that heck most biigger motors wont .but that would go down to upper 40s ft/lbs in sae numbers but its still to high.A good 904 makes around 85hp and around 65 ft/lbs but they dont make alot of torque untill 4500 to 5000.will your bike lift the front wheel a foot of the ground if you wack the throttle in 1st gear at 2500?
If not your not makeing 50 ft/lbs at 2500.trust me I know this from much testing.

 

[mike-tt special]

ok for the sake of clarity and because this is a american forum i will use the sae scale from now on.

mike i don't see why you are quite happy to accept the dyno figures of 83hp peak and 60lb/ft peak but think there is something wrong with the lower part of the chart,
all thats happened is that due to better design my exhaust has filled the hole in the torque curve that the d&d 2-1 creates, if you know how to doctor certain areas of dynojet 250i charts your smarter than me or my dyno operator.

also for clarity the 904 power figures of 85hp and 65lb/ft torque that you quote mike i presume are for your 904(the one that you posted dyno charts for in the dyno thread) which has more engine mods than mine i.e 42mm mikuni(worth 5-10hp) and 813 cams(worth 5-10hp), so with the addition of 42mm tb's to my bike should put me around 88-93hp sae and the addition of 813 cams should put me around 93-103hp

by the way mike i risked life and limb to try the wheelie test in sub zero temperatures here but i did it at 3000rpm because that is where it makes 50lb/ft sae, and yes it does!.

 

[mikeinva]

its more a mater of not enough cc to get that much torque at low rpms.how could the dyno be off on torque?torque is figured by the tach signal on dynojet machines .hell i saw one on my bike once that said it made 110 ft/lbs lol i knew that wasnt right.I do agree if you are running stock tb you are getting about all it will do on top end.You maybe on to something with the pipes giveing you low end I cant say your not that is a very flat torque line .I am just saying i think it maybe reading alittle high.It doesnt mater though if you used the same dyno before and after you know you have gained thats all that really maters anyway.Look at it this way supose the dyno tach is off 500 to 1000 rpms then you would be in the 3500 to 4000 rpm range and that i would say was right.
Dont go by my dyno readings with the 42s as far as anything under 4500 I had the guy roll on the throttle slow I did not have acell pumps right back then.I dont care abou any thing under 5000 rpms on the dyno I am only looking for what main jets make the most hp .I set the low end up by what takes off the best on the road the dyno cant tell you that,you must go by feel and what the a/f gauge tells you.

 

[mike-tt special]

i see where you are coming from with the dyno tach reading 1000rpm low theory but since i have set my ecu rev limit at 8250rpm and that is where the dyno tach cuts there can't be any error there.

i think it's worth pointing out at this stage that steve hammond at motrac racing who did the dyno runs is a very experienced engine biulder/tuner and dyno operator(one of the first dynojet dynos in the uk). he has done development work for shell oil and engine biulding/tuning work for british superbike teams.

 

[mike-tt special]

so with the addition of 42mm tb's to my bike should put me around 88-93hp sae and the addition of 813 cams should put me around 93-103hp sae

a pretty accurate estimate I think that supports my belief that my exhaust exceeds the performance of the D&D 2-1

dyno graph of the addition of 44mm tb's showing peak of 96hp din/ 92.14hp sae

 

[CHRIS211083]

Hi MikeTT,
Do you have a Dyno run picture of your 44mm throttle Tpusa 904. It's not in the Dyno section anymore either.
I have screen shotted your Weisco one here.

 

[mike-tt special]

I've no idea why the Wiseco 904 with 44mm tb Dyno graphs have been removed from my post, but here's the HP graph again for you.

44mm tb 70%-75%-100% dyno graph

www.triumphrat.net

 

[CHRIS211083]

Wow what a difference the 44mm throttles made. Great numbers mate, hope to get close to that myself.

 

[mike-tt special]

Yes, an increase pretty much across all the rpm peaking with 10hp at the top.
And as you say on your thread, the extra push from the torque gain from low rpm to max rpm makes them very rapid.
I've shocked and embarrassed quite a few guys on superbikes with either a drag race from the lights, or the drive off corners. As long as there aren't enough straights long enough to get over 80-90 mph they can't get away from me and more than one couldn't keep up with me lol.

 

[mike-tt special]

Here is the torque graph, notice that 80% of the max torque is being produced by 2500rpm, that is why they feel so strong 😎

44mm tb torque dyno graph

www.triumphrat.net

 

[CHRIS211083]

66lbft is a great amount, fingers crossed I get a similar peak.

I had a peak of [email protected],400rpm onwards which would have started sooner if not for a overly rich mixture into a lean mixture. I can honestly say the new head has given me so much more bottom and mid range. Can't tell about top end yet as the fuellings off but come Wednesday I'll have some rough figures. Don't think the fuelling will be right but it will give a good start point.

 

[mike-tt special]

Looking at your a/f trace reminds me why I got a efi bonnie and why I'm converting my 91 zxr750 to efi! Lol

I noticed in your big bore thrux thread that you are having big problems getting the fuelling dialled in, do you think lowering the float height will lean out the bottom end on the pilot jet and let you use a richer needle setting, and a richer main jet?

 

[CHRIS211083]

This was before the head swap, so has no bearing on the current fuelling but yes the dance of the jets and needles has began. I've got a few options to try tomorrow to get the fuelling as close as I can for the Dyno on Wednesday.

 

[barnettbob29]

hmmm! were you expecting a pic of the d&d tt exhaust, this is my own custom fabricated tt style exhaust its in the pic in your post.
it has what i consider many improvements on the d&d, namely:-
proper tapered headers not just a stepped pipe
balance pipe between the under belly silencers with a lambda sensor take-off
spring retained slip joints to make it easier to take of to do oil+filter change (and spring retained joints look much cooler!)
tucked in tighter under the engine for better ground clearance
better noise suppresion from the under belly silencers and the mini cones
heres more pics from a different angle

THAT is the Triumph look I like

 

[CHRIS211083]

Hi MikeTT, what made you choose 46mm headers? Also you say they are tapered ? What diameter did you taper to and how did you go about finding this info out? Just curious really. I've been thinking about the D&D 2-1. I wonder if they designed it for a stock size engine? Or a bigger bore motor. I know it makes the most power but I wonder if there is more to be had with slight design tweaks. It was after all designed for the Thruxton cup so stock engines. Wonder if larger headers would be better?
Look forward to your opinion.

 

[mike-tt special]

I went with 46mm because it's the same diameter tube that D+D use in both their systems, I was having a little bit of fun with mikeinva by saying 46mm instead of 1-3/4" .....it's virtually the same diameter lol.

I figured that if the D+D at 1-3/4" (46mm) makes good power on mike's 1087 monster but also many guys had good results on fairly std bikes fitted with the same D+D's then 46mm is a good size.
But I also noted that the D+D didn't do so well at the low/mid rpm, so I reckoned I could improved things there, which looking at my Dyno graphs compared to other similar spec 904's, I think I achieved?

Tapered headers on a 4 stroke work in a similar way to expansion chambers on a 2 stroke, the D+D does it very crudely with a stepped header, I simply used a tapered section in the header to get a better spread of power (especially at the bottom/mid rpm without losing anything at the top.

 

[CHRIS211083]

1 3/4" is 44.5 mm not 46mm. I was wondering if you went up a couple mm because our bikes have more CC and power than stock. I see what you achieved with your exhaust and it's great. Just curious if I should go with 46mm or stick with the 44.5 or 45mm headers. It would be interesting Mike to get a back to back comparison between your exhaust on the Dyno Vs the D&D 2-1. Pm me if your up for this. Will be interesting to hear what Harrison Performance exhausts recommend.

 

[mike-tt special]

I did say that 46mm is "virtually" the same as 1-3/4!.......but yes if you want to be pedantic 46mm is 1.5mm bigger than 1-3/4.
Its 46mm because that was the nearest size stainless steel tube the guy had at the time, If mike's 1087 monster can make great power with a 44.5mm diameter exhaust, I don't think there would be any discernable peak power difference between a 44.5mm, 45mm or 46mm diameter exhaust.

Yes it will be interesting to hear what Harrison exhausts come up with for your bike.
I have a highly tuned 91 zxr750 with a Gibson made replica of the wsb muzzy exhaust that had tapered headers. And I am familiar with Harrison's work in making replica exhausts with tapered headers for the zxr/zx7r Kawasaki's that are having a resurgence in classic TT and golden era superbike racing.