Bullet Ride's 2.8L Stroker Project (Updated: Dyno Plot pg. 6)

[darvo]

What compression ratio would your engine have with that setup?

[Bullet Ride]

Yeah, my 10gb bandwidth limit got maxed in two short weeks.... too many people are looking at my build threads lol.

I need to start hosting my pictures somewhere that has more bandwidth.

In the meantime, you can just right click on the picture and select open image in new tab if you want to see it. Bandwidth is unlimited if viewing the pictures directly on the photobucket website.

[cgk_iii]

all the pictures dont show up on my mac anymore.. :( now its just a bunch of photo bucket bandwidth crap.. ive been following this thread for a while now too..

[Ether-D]

Then my kids are on their way...
Again, great write-up.

[Bullet Ride]

What did your parents do (or not do) to make you such a badass? I've got three kids that I want to become doers.

Beautiful build. I'm doing the m50b28 crank and e rods right now on my spare motor.
Really inspiring...

haha, well my old man is a definitely a handy man. I remember hanging out in the garage with him when I was young handing him tools while he worked on the family car. That definitely played a part. Also, me and my two brothers were always interested in tinkering with mechanical things when we were kids, whether it be our bikes, or taking apart our toys (and never quite getting them back together properly lol). Suffice it to say, we all ended up going to university for mechanical engineering

[Ether-D]

What did your parents do (or not do) to make you such a badass? I've got three kids that I want to become doers.

Beautiful build. I'm doing the m50b28 crank and e rods right now on my spare motor.
Really inspiring...

[digger]

But you can see that the slope of the torque curve as it ramps up is essentially the same between when it was advanced and now when it's been retarded. My torque does come on a bit steeper, but the scale of the y-axis makes it look a bit steeper than it actually is when compared to the plot below with a y-axis that starts at 0.

The exhaust ports have been gasket matched and smoothed out a bit, that's the only head work I did...

easy way to tell is wait for the next dyno day that will end speculation.

[Bullet Ride]

IMO the car comes on cam much more steeply which suggest non idea timing events (later inlet valve closing point), i would not necessarily expect it to be like stock, the exhaust lobe is only a 272 and you are 12% more engine size with no headwork?

But you can see that the slope of the torque curve as it ramps up is essentially the same between when it was advanced and now when it's been retarded. My torque does come on a bit steeper, but the scale of the y-axis makes it look a bit steeper than it actually is when compared to the plot below with a y-axis that starts at 0.

The exhaust ports have been gasket matched and smoothed out a bit, that's the only head work I did...

[digger]

No, but if the cam is timed correctly shouldn't I expect the overall shape of the curves to be similar to a stock M20?

Here's a comparison between my latest dyno and a bunch of SpecE30 cars, the shape is very similar...



There will be some proper dyno play coming this summer. I'm looking at converting my car over to a wasted spark set-up so I can keep the cap and rotor off the motor, that'll make it much easier to play with the cam gear when on the dyno.

IMO the car comes on cam much more steeply which suggest non idea timing events (later inlet valve closing point), i would not necessarily expect it to be like stock, the exhaust lobe is only a 272 and you are 12% more engine size with no headwork? the exhaust side cant evacuate the exhaust gas and you end up with residual exhaust gas in the cyl preventing some inlet charge coming in as rpm rise and then the small duration creates higher pumping losses and hp starts to fall.

if you ran a 284/284 then it would be peak higher. that much split on the cam doesn't make much sense on the M20 the exhaust flow is not very good as it is so it is bandaiding something. on mine it bandaids having lack of P to V on the exhaust side with MM pistons....

alternatively more CR with retarded cam helps

play around on the dyno and try, look to improve the average power of the curve don't look at peak so much

[Bullet Ride]

Unfortunately the DIYPNP only has 4 ignition outputs, so even with individual coil packs I'd have to run wasted spark. I'm probably going to use a coil pack off of a GM 3800 because they are a dime a dozen at the scrappers and upgraded coils are easy to come by.

[tinkwithanr]

Nice graphs.

Any reason your planning for wasted spark as opposed to individual coil packs?

[Bullet Ride]

one thing for sure is small cam + big engine does not peak at high rpm unless something is mismatched terribly

No, but if the cam is timed correctly shouldn't I expect the overall shape of the curves to be similar to a stock M20?

Here's a comparison between my latest dyno and a bunch of SpecE30 cars, the shape is very similar...



There will be some proper dyno play coming this summer. I'm looking at converting my car over to a wasted spark set-up so I can keep the cap and rotor off the motor, that'll make it much easier to play with the cam gear when on the dyno.

[digger]

Confusion is definitely coming from the fact that two different machines were used. The guys at the shop do call it "the heartbrake dyno" because cars usually see lower numbers on it than they'll see on other dynos. I can say that the car definitely doesn't feel like it's noticeably missing any torque compared to when the cam was advanced, and last year above 5500rpm the car really felt like it was falling flat, which it shouldn't be with a 284 cam. I've got nice square HP & TQ numbers now which is what I was expecting out of this set-up.

You definitely should install an adjustable cam gear if you're going to put in an aftermarket cam and/or having your head and block machined. As you can see from my results it's important be able to dial things in.

guys who run these sort places always say that....dont even worry about comparing the two graphs and reading too much into it.

i have done shitloads of dyno tests, air filters/boxes, x-pipes, exhaust back pressure, port matched intake manifold, camshaft and timing, exhausts. seat of the pants doesnt work in 90% of cases....... lots of times i though something was better but it wasnt and vice versa.

one thing for sure is small cam + big engine does not peak at high rpm unless something is mismatched terribly

[go3go]

Just read through the thread. Amazing build and the car sounds mean! I'm hoping to do something along the same lines next year when I graduate, and will definitely be referring back to this. Thanks for the documentation!

[Bullet Ride]

Does the result of the cam timing change feel like your 'wishful speculating'? You'd think that you'd have noticed if the torque had dropped off as much between 3k and 5.5k as the dyno comparison shows. I'm interested because I'm putting together the same cam and motor setup and was just going to use a stock cam gear.

Confusion is definitely coming from the fact that two different machines were used. The guys at the shop do call it "the heartbrake dyno" because cars usually see lower numbers on it than they'll see on other dynos. I can say that the car definitely doesn't feel like it's noticeably missing any torque compared to when the cam was advanced, and last year above 5500rpm the car really felt like it was falling flat, which it shouldn't be with a 284 cam. I've got nice square HP & TQ numbers now which is what I was expecting out of this set-up.

You definitely should install an adjustable cam gear if you're going to put in an aftermarket cam and/or having your head and block machined. As you can see from my results it's important be able to dial things in.