2017 engine build

[fordracing65]

Traction control should be a game changer for you. I can't wait to see the dyno sheet.

[Cobra #3170]

Originally Posted by fordracing65

Traction control should be a game changer for you. I can't wait to see the dyno sheet.

So many people were cheating last year that they just gave up and made it legal for Goodguys. My understanding is that ABS and electronic shocks will also be legal in 2017. Looking at computer data we were below 1900 rpm in 3 corners so the main emphasis is getting minimum RPM higher and then being able to run 9000 rpm reliably. I have a 4.88 rear gear ready to go in so we should be better getting off tight corners. Engine acceleration should be much better too but I suspect we will lose horsepower.
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.

[1795]

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.

[1795]

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.

[Cobra #3170]

Originally Posted by 1795

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.

Funny you should bring the "light lift" up, that is how the car is set up. I like the way my GT3 Porsche handles IE don't brake just lift so we set the Cobra up to handle the same way. A light lift transfers enough weight for turn in then throttle application makes the car go neutral. It works really well at the autox's we run.
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.

[1795]

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.