building a 4.1 or a hot air 85 3.8 which is better?

[michaelshobby]

wanting a hot street car 750bwhp goal.I have either one to choose from.Just want to hear what you guys think.

 

[sixgun86gn]

For 750 whp choose neither. Get a stage 2 block or try a girdled and capped 86-87 block.

I have personally had a 4.1 that had 500 rwhp at low boost and would not recommend much more than that.

 

[wickedtt]

I have personally had a 4.1 that had 500 rwhp at low boost and would not recommend much more than that.[/QUOTE]

Why not ? What was involved in your 4.1 build that it wouldn't take more than 500 rwhp?

 

[novaderrik]

a lot of people that read in magazines and online about cars making more than 500hp have no concept of what that much power is like or how much work and money is required to make that much power and have it hold together for more than a few WFO blasts..
500hp at the flywheel is enough to make most people crap their pants- 500 at the wheels is borderline insane for anything that actually gets driven on the street.

 

[sixgun86gn]

I have personally had a 4.1 that had 500 rwhp at low boost and would not recommend much more than that.

Why not ? What was involved in your 4.1 build that it wouldn't take more than 500 rwhp?[/QUOTE]

because that is around 620hp at the flywheel and most blocks split in half somewhere around 650. Except stage 2 blocks or the TA block.

 

[Nick Micale]

wanting a hot street car 750bwhp goal.I have either one to choose from.Just want to hear what you guys think.

I see you are new here, so it would be better if you were to state your goals and what kind of car and mods it has, if any?

"hot street car" covers LOTS of ground.

There is more to a "fast" car than just a HP number. Since most of us have a budget that is somewhat limited, that is also something else that needs to be included in a fruitful discussion on "how fast".

Generally, for a street build I have found the 4.1 to be the better choice, not sure about 700bwhp though?

My first 4.1 build years ago ran easy mid-10's, and it was still a street car then. :biggrin:

 

[Dynalow00]

My first 4.1 build years ago ran easy mid-10's, and it was still a street car then. :biggrin:[/QUOTE]

Any idea what the rwhp was for that build (as a reference for the OP)? Any build specs?

The motor in my sig will be up and running soon- I am looking forward to some mid-10 passes and a fun street car. I am hoping the 4.1 will survive...

 

[Mad_Trbo]

Curious George too

I am curious to know what that 4.1 build looked like too.

 

[Dynalow00]

Mad Trbo- Whatever happened to the build you guys did? I was following it in another thread..

 

[bison]

wanting a hot street car 750bwhp goal.I have either one to choose from.Just want to hear what you guys think.

I think id use an aftermarket block as rec'd already. 750whp is not typical of a street car and most of that power wont be usable at legal road speeds. Very low 9 sec TR's have 750whp. You need to have everything in line to handle the power and have decent reliability. Its a $20k project at minimum

 

[Mad_Trbo]

Thanks for asking

Dynalow00

We had some teething issues, in other words an opportunity to learn. Learning from mistakes is probably the best way to do that.

As an example I had fuel delivery issues as recently as a week or so ago. Trying to keep things as stealth as possible I had my external pump pulling up to feed itself and it didn't like that (how many times have you heard don't make the pump pull up hill). And I had the same size line feeding the pump as I had feeding the rail so I had several issues compounding upon themselves. I recently purchased a new fuel tank that is sumped and works better with the external pump.

Aside from that I've been running around town now for a couple of months getting my street tune down and I feel everything has finally been worked out.

I plan to get on the dyno for a pump gas tune and see what she does. I'll have to keep you in mind and let you know seeing as you are traveling the same route.

Our builds ar slightly different but should yield somewhat similar results.

Much success with what you are doing, getting it down is definitely rewarding.

 

[Dynalow00]

Cool- Glad to hear it's breathing! I am going to keep a close eye on my tune- I am hoping the pump/injector combo I have is enough. I may need to go external eventually, especially if a larger turbo is installed. For now I am looking forward to trying out the 6765.
I kinda wish the 4.1 guys had their own 'Tech area' or sticky. It was a little tough finding other guys doing similar builds. Fortunately, a local guy (Powder) had just finished a build that came from the same machine shop as me. I should have mine installed soon, and the tuning/testing shall begin....:biggrin:

 

[Rell87]

a lot of people that read in magazines and online about cars making more than 500hp have no concept of what that much power is like or how much work and money is required to make that much power and have it hold together for more than a few WFO blasts..
500hp at the flywheel is enough to make most people crap their pants- 500 at the wheels is borderline insane for anything that actually gets driven on the street.

Very expensive

I've been working on mine for 4 years. Look at my cardomain link for specs/pics