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2017 engine build
Picture shows new small journal rod for 9000 rpm FE engine. Sonny Briant
Timkin steel, center counter crank is not here yet, will post pictures when it comes in. http://clubcobra.com/photopost/data/...weight_rod.jpg |
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Bruce
I'm really glad to see you doing the changes to the FE....I look forward to your success with the motor......is Kinetics doing the motor....?? I ran out of money ....but I wanted to try some of the Ideas you are doing.....I believe it could become a very reliable and strong motor....keep us abreast of the progress..... |
Engine
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Yes Kinetics is doing the new one too, I have had so much good luck with them for over 23 years on 5 different engines I would not go anywhere else. It will be interesting to see how well it works, was turning the old one 8200 on a regular basis and it looked like new inside other than some valve guide wear. |
Valve Train
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Yes using small stem titanium intake and exhaust valves to keep the weight down and a new cam with more exhaust duration and lift, intake lobe will be similar to today's 281@ .050 and 297 @ .050 exhaust both right around .800 lift a little more aggressive ramp in the middle. Using the very best NASCAR springs this time. The old engine pressures were still at installed levels but thought I should upgrade because of rpm. They are supposed to be better material. Individual roller rockers and .125 wall 3/8" trend push rods. !5 to 1 compression ratio with smaller chamber and a slight pop up on piston. Trying Line to Line coating process on pistons too. The crank should be a work of art according to Kinetics. Head flow is around 380 cfm so that is the limiting factor although we will do some manifold work too. Installing a modern EFI this time with traction control because it is legal now in Goodguys. |
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That's great to hear... as you may or may not know Kinetic's built our motor and our motors used a lot of the same componets ..... I remember seeing your block when it was in pieces and they welded it back together and rebuilt the whole engine .... I've been very happy with my motor ... I believe the only difference was the Fuel injection you were using and ours used a Holley 4500 Carb.... we were shooting for Road America where we could open it up down the 3 big straight away's and it worked great.....we were only running 7500 rpm's.... But I always wanted to make some changes for some of the shorter tracks... but never got there.... I'm excited for you and will be watching all of the development you come up with .... I'm just a FE Fan and once we got the breathing issue worked out... it to me.....was a motor to be dealt with Keep us abreast of your progress. and get Chris to take lot's of photo's... Morris |
Traction control should be a game changer for you. I can't wait to see the dyno sheet.
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Traction control
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Torque will likely be in the mid 500's now but we had too much anyway. It is a real gamble because the 498 engine was really strong everywhere just hope I made the right move. The cars handling and brakes are close to optimum now so this was the only place we could potentially pick up time over last year. All our competitors are going nuts with either mods such as $10,000 Bosch racing ABS units and GM electronic shocks or even all new cars. We probably showed them too much speed in November but I like to go for it as does Scott. Robby Unser chastised us for showing our entire hand but I liked seeing their reaction to the cars speed. Good old shock and awe, of course that just spurred them on so maybe Robbie was right. |
What rpm range do you plan on the power band being in? A 4.88 ratio will raise your rpm's in the tight corners above the 1900 range, but it makes me think that you want to make sure that you are not too much into the power band at that slow of a speed, as you might risk breaking the tires loose with all that power.
It's tough for me to comment, as I have not auto crossed, only road raced and therefore we are approaching our corners differently in some aspects and similar in others. Sounds like an interesting build. |
As I think about it, this combination might work out well for you and have some added benefit. The 4.88 rear end will allow for quicker acceleration out of corners, with the cost of lowering top speed for each gear on the straights, but being able to approach 9,000 rpms will make up for that and decrease the need for an upshift at the end of longer straights.
The combination of the 4.88 rear end and 15:1 compression ratio will probably result in quicker de-acceleration when you take your foot off the gas and this may result in you being able to take corners with just a light lift that previously required some braking. A quick lift and turn in may be all you need, or at least you might only need lighter braking than previously. Anytime that you can eliminate some form of driver input, such as shifting or braking, you will lower your time. Looking forward to hearing how things work out once you get it all back together. |
Cornering
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The car will have close to the same top speed in each gear as it did with the 4.27 rear end the difference being that it will have a higher minimum rpm and keep port velocity in a working range. All small changes but hopefully worth about 1 second on a 60 second course. |
Exactly! A light lift will transfer the weight to the front wheels at turn-in and then you can quickly accelerate. No time wasted going to the brake and should shave off some time. A few of those could end up in a second quicker time.
You will probably have to experiment a little to see how much of a lift is required and for how long. I would suspect that with that setup too much of a lift could risk breaking the rear end loose due to the amount of engine braking combined with the gear ratio. |
New 2017 engine
Here is a photo of the new Sonny Bryant short stroke small bearing crank. Note center throw counter weight. 9300 rpm can't be far away!
http://clubcobra.com/photopost/data/...ht_crank_2.jpg[/url] |
Pretty impressive! Looks nice.
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very interesting
Tell us more Dwight |
Engine Build
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Wow !! It's great your working the FE. I am still stuck in 1970 :JEKYLHYDE
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New engine bore = 4.32 stroke = 3.75 |
By my old rule of thumb you are likely giving up 75 ft-lb of torque, but if you spin it to 9300 you should make the same Hp as the bigger motor made at 8200. Since you changed the ramps on the cam, you should pick up a bit more power.
I'm not sure that you are going to gain anything in the usable power range, in terms of MPH of the car, assuming that the gear ratio change has you running the same speed at maximum rpm of both engines. At least in theory you would need ~13% more rpm to put the same Hp to the wheels at the lower torque output. Wherever the torque dropped off (on the low rpm side of the torque curve) happen on the long stroke, it should happen on the short stroke at 13% higher rpm. So the usable torque range of both engines should give the same speed range, even though the rpm range of the short stroke is a bit longer. That said, theorys don't always hold water. Since you said you already had too much torque to start with, I would bet this is going to help you out a bit. You may have to play with the rear end ratio a bit. I'm thinking you do not want to drop the ratio as much as the stroke ratio was changed. Maybe half way. Keep us informed, I find this quite interesting. |
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