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Intake Manifold Throttle Body Position


WallerZ

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I'm redesigning my quickly bodged together intake manifold as we found it appearing to be possibly restrictive at the top end. As some of you may have seen, it currently sticks out the top of the bonnet and even with a thoughtful redesign, it is unlikely to fit under the bonnet at all.

I'm currently figuring out throttle body placement and wondering if there is any adverse effects with mounting it on the front face or the back face of the manifold? It will literally be directly fitted with a cone filter regardless of position (unless someone suggests otherwise).

I'm currently tipping towards the front due to ease and bonnet fitment (plus a ram air effect at speed?!?) but would like any input if anyone has experience in this area?

Cheers,

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A single throttle body, right? I don't think it matters then. If you've got individually bodies then there can be issues where the more forward of them picks up cleaner/cooler air than those behind - not the end of the world, I believe you can compensate for this with body tuning and ECU parameters, but if all your air is coming through a single body then it's not something you need to worry about.

 

Ram air I wouldn't get too excited about, it might work on motorbikes pulling 14,000rpm with nice, clean high pressure points on the nosecone and massive airboxes... I'm not particularly sold on it for our purposes though :). I think induction tuning is quite an art...

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When I blanked off around my radiator to improve cooling I put a dedicated air intake pipe from the front grille to the carbs and it made absolutely loads of difference to the engine performance. I suppose it depends on how bad it was in the first place.

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Its currently sat out the bonnet in fresh air, so cold air or hot air isn't an issue. Its the actual manifold design thats the issue, made in a rush from what I could get hold of easily so I could make the Wales trip. I was curious if there was substantial benefits or losses from having the throttle facing forward vs backward.

 

A single throttle body, right? I don't think it matters then. If you've got individually bodies then there can be issues where the more forward of them picks up cleaner/cooler air than those behind - not the end of the world, I believe you can compensate for this with body tuning and ECU parameters, but if all your air is coming through a single body then it's not something you need to worry about.

 

Ram air I wouldn't get too excited about, it might work on motorbikes pulling 14,000rpm with nice, clean high pressure points on the nosecone and massive airboxes... I'm not particularly sold on it for our purposes though :). I think induction tuning is quite an art...

 

Thanks Dan, if its a fine art with squeezing out every 0.1bhp then I reckon I'll be ok ;) Just wanted to check I wasn't going to cause more issues or large power drops. I'll have a mock up to see which is easiest and most aesthetically pleasing, and go from there :D

Cheers

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Guest lotusPaul

Just to add. Intake pulse tuning is just a simple maths equation. Very simple to do BUT is only effective at a predetermined revs. Ie you tune for say 3500rpms. Thats not to say that +/- 250 isnt effected, it is.

In essence it was more effective on IR systems.

Basically you want the longest you can, as this moves the pulse tuning down the rev range, but the trade off is a less responsive engine.

For example look at my 1600cc twin cam running efi on jenveys. Peak torque should occour at 5500rpms. By fitting longer ram pipes (assuming they fit correctly) i can tune for peak torque to say 4500 rpms. This will have the effect on the dyno at raising at that point but my impeed and lower the overall 5500 previously achieved.

 

Without seeing your setup, i would sugest that you look at fitting the bigest air filter you can, into a sealed box, in the coldest part of your nose cone, and feed it into your engine. The cold dense air will be better for you across the entire rev range.

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Paul mate, relax lol. I asked about throttle body position A or B, I'm bunging a 20 year old engine into a chassis that is in essence 60 years old for fun, not designing the next F1 racing engine 😉 haha. Its a V6 with a centrally mounted intake thats already blocking my view and doesn't have space to get much lower lol.

I appreciate the input, but I was looking for a simple option of position A or B, coz its less likely to devour small children and pets etc incase I'd overlooked anything basic 😁

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