Hennessy GT700 engine upgrade

[GT4JR]

Has any of you GT owners upgraded their engines as per the Hennessy GT700 specs and is there any cons doing it? cost of this upgrade? Can it be done in a tuner shop in CA?

Thanks!

 

[B O N Y]

Has any of you GT owners upgraded their engines as per the Hennessy GT700 specs and is there any cons doing it? cost of this upgrade? Can it be done in a tuner shop in CA?

Thanks!

I am sure, do a search.

 

[californiacuda]

I went to their website and the main power adder that is being done is reducing the stock supercharger pulley (wheel) to a smaller size, to increease the rpms it makes in relation to engine speed. By making this change more air is forced into the engine creaing more boost pressure.

There are several suppliers who make smaller pulleys. A question to Hennesseys would be, how small of a pulley are they putting on the sc. 2.7" is a common size reduction upgrade. Kenne Bell makes a sc snout replacement that allows a pulley size reduction to 2.5"

Additionally, a computer reflash needs to be done so that the engine takes into account the increased airflow. There are many companies, including Hennesseys that are offering these services.

 

[californiacuda]

Also, I believe the figure they are giving 700hp is an estimate of engine hp. Most figures discussed on this forum are hp/torque at the rear wheels.

Engine hp will be approx 15% higher than wheel hp due to drive trains loss. So, if you measure their 700 upgrade at the wheels, it would show around 600hp. Companies like to advertise the higher number, obviously, it sounds more impressive. Its important to know the difference.

 

[barondw]

Also, I believe the figure they are giving 700hp is an estimate of engine hp. Most figures discussed on this forum are hp/torque at the rear wheels.

Engine hp will be approx 15% higher than wheel hp due to drive trains loss. So, if you measure their 700 upgrade at the wheels, it would show around 600hp. Companies like to advertise the higher number, obviously, it sounds more impressive. Its important to know the difference.

Well said and the numbers should be corrected and smoothed.

Dave

 

[Hennessey Performance]

Our pulley has a 2.68 in. ID and gives approx. 16 psi boost. We feel that this is the max boost to run pump gas. We have supplied this pulley to over 100 GT owners and GT tuner shops. With the other necessary mods 600-640 rw hp has been attained. Our GT700 kit makes around 620 rw hp.

I went to their website and the main power adder that is being done is reducing the stock supercharger pulley (wheel) to a smaller size, to increease the rpms it makes in relation to engine speed. By making this change more air is forced into the engine creaing more boost pressure.

There are several suppliers who make smaller pulleys. A question to Hennesseys would be, how small of a pulley are they putting on the sc. 2.7" is a common size reduction upgrade. Kenne Bell makes a sc snout replacement that allows a pulley size reduction to 2.5"

Additionally, a computer reflash needs to be done so that the engine takes into account the increased airflow. There are many companies, including Hennesseys that are offering these services.

 

[Hennessey Performance]

We do sell the pulley by itself for those who already have the other necessary mods. It comes black anodized and looks factory and works with the factory belt. We have about 40 of them in stock. PM or call for pricing.

 

[californiacuda]

Thanks for the info, are you working on any Whipple or TT GTs? And, what do you do to the Vipers irs to get them to handle so much power?

 

[Hennessey Performance]

Thanks for the info, are you working on any Whipple or TT GTs? And, what do you do to the Vipers irs to get them to handle so much power?

Building 2 GT TT's right now. Have not done a Whipple yet. We install a Quaiffe center chunk upgrade in the Viper diff and havent broken one yet.

 

[GT4JR]

Thank you for your input, Californiacuda; have you made any mods to ur car and what exactly and was it at a shop in Southern CA?

 

[californiacuda]

I have lost my mind, but here goes. This week, I'm putting a NHRA 8.50-9.99 roll cage in, made out of 1 3/4 chrome molly. The engine is at Accufab getting a complete race build with stronger rods/pistons/ported heads. A twin turbo system has already been fabricated and run.

So, now the focus is to put everything back together. I would like to go to the Texas Mile, but I don't know if the car will be ready by then.

 

[Spirit]

I have lost my mind, but here goes. This week, I'm putting a NHRA 8.50-9.99 roll cage in, made out of 1 3/4 chrome molly. The engine is at Accufab getting a complete race build with stronger rods/pistons/ported heads. A twin turbo system has already been fabricated and run.

So, now the focus is to put everything back together. I would like to go to the Texas Mile, but I don't know if the car will be ready by then.

Cuda,

I hope you can get it done in time, it's gonna be FUNNN !!:biggrin

Would really like to see you there with your machine.:thumbsup

Fred

 

[californiacuda]

Thanks, I'm trying to push things along.

 

[632C2]

I have lost my mind, but here goes. This week, I'm putting a NHRA 8.50-9.99 roll cage in, made out of 1 3/4 chrome molly. The engine is at Accufab getting a complete race build with stronger rods/pistons/ported heads. A twin turbo system has already been fabricated and run.

So, now the focus is to put everything back together. I would like to go to the Texas Mile, but I don't know if the car will be ready by then.

This sounds like a car to "raise the bar". Do you happen to have any progress pics? This I have to see...

Steve

 

[californiacuda]

Right now it looks like the rest of my cars. Like a bomb went off and blew everything apart. By the end of the week the main structure of the cage should be in. I'll post some pics then. Thanks for asking.