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The runner length isn't really the issue with those manifolds its the awful plenum and post TB the the big let down. The plenum is real narrow vertically and very long so it takes a while to fill end to to end (relative terms) If the plenum were to be extended down into the valley which I'm sure it possible and twin TBs so how added which I guess is impossible that would wake them up for sure.

The think is there is no one runner length that suit the engine and a fixed length can and often is tuned for more than one rpm band as short runner for eg might be tuned at 3500 and 5000, being 3500 might be the 5rd harmonic and the 5000 being the 3rd.

On some of the simulated v6s I have designed in software the runners have to be longer than stock as it happen the 3rd harmonic was a possible practical length at 7000 rpm where a stock engine at 4500 for eg sits on 4th. Of course if I use the 4th the 7000 rpm engine will need shorter than stock but that's not possible without a custom intake and 3rd have a stronger amplitude than 4th so better performance.

Im sure if you could have an LS style bananas on a holden V8 with big ass TB it would go really good.

Check out hogans manifolds. There make custom sheet metal intakes and are known to be the best. They even have listed an LS banana manifold entirely made from sheet.

like this. Checked their prices, cheaper than group a and huge variety.

http://www.hogansracingmanifolds.com/im ... 75__2_.JPG

I have tuned a 355 with a star performance manifold on it... its just bananas with some porting done, a new neck and bigger TB.... the only 355 with bananas I have ever driven that makes power to 6500.... normally they fall over at 4900... I was surprised... it just proves the runners are fine, tis the plenum/neck/tb that is the main problem.

https://jhp.com.au/shop/performance/hol ... hangeover/

Jayme wrote:I have tuned a 355 with a star performance manifold on it... its just bananas with some porting done, a new neck and bigger TB.... the only 355 with bananas I have ever driven that makes power to 6500.... normally they fall over at 4900... I was surprised... it just proves the runners are fine, tis the plenum/neck/tb that is the main problem.

https://jhp.com.au/shop/performance/hol ... hangeover/

and I've tuned a 355 with the stock manifold and its sooo noticeable when it falls over just over 4500rpm .... just really starting to work and then smack, handbrake on!

vlad01 wrote:

Jayme wrote:I have tuned a 355 with a star performance manifold on it... its just bananas with some porting done, a new neck and bigger TB.... the only 355 with bananas I have ever driven that makes power to 6500.... normally they fall over at 4900... I was surprised... it just proves the runners are fine, tis the plenum/neck/tb that is the main problem.

https://jhp.com.au/shop/performance/hol ... hangeover/

So would you recommend going that way ? Do you mind sharing engine specs and was it dyno'd ? Is love to wake mine up but don't want to loose low down and drivability

sorry, it was a road tune.. I dont know the other engine specs other than it had a bigger cam than stock. it did retain the low down drivability and performed way better up top than normal bananas. after feeling the low/midrange power loss from a torque power dual plane, I would sooner use modified bananas.

Jayme wrote:sorry, it was a road tune.. I dont know the other engine specs other than it had a bigger cam than stock. it did retain the low down drivability and performed way better up top than normal bananas. after feeling the low/midrange power loss from a torque power dual plane, I would sooner use modified bananas.

Maybe I've read it wrong did you notice with a torque power dual plane there was a loss at low rpm over a stock intake?

yes for sure. the car in question is only half tuned (needs bigger fuel pump) and it has a 286 cam. all we changed was stock intake for tp dual plane, and the instant loss of bottom end power was very noticable.

That's good to know about the dual plane, I've got a spare bunch of bananas may have to get the grinder out and see what we can do, be nice to gain some top end I can feel the motor still pulling strongly until it hits the wall, I just don't want to loose the low down

Jayme wrote:yes for sure. the car in question is only half tuned (needs bigger fuel pump) and it has a 286 cam. all we changed was stock intake for tp dual plane, and the instant loss of bottom end power was very noticable.

Very interesting thanks. Was the bananas ported bigger throttle body or dead stock? I think the throttle body opening is 70mm but the neck tapers off?