2.4 lt big four Exhaust ?'s Options

[JRust]

I bought nice set of SS HE along with a dual tip Triad Muffler a while back. I got them from John Kelly (Ghia Specialties). He had them on a big 4 also. Just wanted some input as to wether these will be sufficient? I would like to retain my heat if possible. The carbs are 48 weber's I believe. Not sure on the jets or anything yet. Bought the engine from Craig at Camp914. The only problem is we don't have any build info on it. I figure to put it in & see how it feels/runs.

This may be a dumb question but it was built off a GC 2.0 engine. Are the spark plugs different when you build a big 4 or do you still use the stock plug & gap? Obviously this is a new arena for me with the big 4. Any advice is much appreciated. I am hoping to put it in early next month. Just getting to prepping/fixing my engine bay while it is empty (IMG:style_emoticons/default/blink.gif)

[Jake Raby]

The TIV is all about exhaust!! This engine is more exhaust dependant than most any other due to it's exhaust and intake port designs.

At 2.4L the exhaust is very critical to every aspect of the engine from rev range to MPG and running temperatures. I have, on many occasions seen a 20HP difference between 2 exhaust systems back to back in my lab, just last week I saw 27 HP between 3 different systems on a little 2.0L race engine.

It does sound like you have a bit of a misconfigured arrangement with those big 48mm Carbs and the exhaust that you mention. We START to use a 38mm carb at 2.7 Liters and up to that point a Weber 44 or Dell 45 always makes more power thats usable.

The largest engine I run through stock heaterboxes is my 145 HP 2270cc Daily driver spec engine. Development and direct experience has proven that anything over this needs a much more effective exhaust system and most of my builds have the Tangerine Racing system mandated.

Without proper exhaust we could never reach the insane power levels that we have today. It never ceasdes to amaze me how guys will spend thousands of diolars on induction, compression and cam/ head work only to bolt on a 300 buck exhaust and compromise the rest if the engine.

Exhaust IS everything.

BTW- reading plugs on unleaded gas is near impossible to do with any repeatability at all..

[JRust]

The TIV is all about exhaust!! This engine is more exhaust dependant than most any other due to it's exhaust and intake port designs.

At 2.4L the exhaust is very critical to every aspect of the engine from rev range to MPG and running temperatures. I have, on many occasions seen a 20HP difference between 2 exhaust systems back to back in my lab, just last week I saw 27 HP between 3 different systems on a little 2.0L race engine.

It does sound like you have a bit of a misconfigured arrangement with those big 48mm Carbs and the exhaust that you mention. We START to use a 38mm carb at 2.7 Liters and up to that point a Weber 44 or Dell 45 always makes more power thats usable.

The largest engine I run through stock heaterboxes is my 145 HP 2270cc Daily driver spec engine. Development and direct experience has proven that anything over this needs a much more effective exhaust system and most of my builds have the Tangerine Racing system mandated.

Without proper exhaust we could never reach the insane power levels that we have today. It never ceasdes to amaze me how guys will spend thousands of diolars on induction, compression and cam/ head work only to bolt on a 300 buck exhaust and compromise the rest if the engine.

Exhaust IS everything.

BTW- reading plugs on unleaded gas is near impossible to do with any repeatability at all..

SO I got a chance to go check out my carbs. Here are the numbers on my Webers 40 IDF 19 1F . I guess my estimate of 48 idfs was a little off. I just noticed the air filters seemed so big. Guess I am used to the 36's that were on my 1.7. I am looking at doing the install in 2 weeks. Hopefully I make good progress this weekend. Then the following weekend hopefully I'll be ready to put it all in. (IMG:style_emoticons/default/chowtime.gif)