Joe Soucy

Are there any benefits to porting/boring out the intake holes on the intake to the throttle body to match? in my case I am running a 58mm on my 383 lt1.

atlantadan

Running a 58 mm tb without porting the intake to match will negate most of the perceived benefits of the larger tb.

TheUrbz

uhh yea man, think about it. youre taking an over sized orifice and restricting it down to the original size by not opening up the intake. Much like dan said, if you didnt do that, then you havent been running a 58mm in reality.

myltwon

iTrader: (1)

It's like running a 3" exhaust to a 2 1/4" muffler

BALLSS

do the 58mm blades even open fully into a stock (54mm) intake opening??

but even if they did....bigger opening going into a smaller opening = negative flow vs +

larger TB require PCM programming....or automatic tranny failure will soon follow

Joe Soucy

Let me rephrase my question ... I fully understand that it wouldn’t work . What I’m asking is what are the hp gains or benefits as in like throttle response from a stock or 52mm to a 58mm ...

atlantadan

If you don't port the intake, you won't see any gains or changes. From my own experience, when I did my 58mm and intake I noticed a better throttle response and that's about it. Never been on a dyno so I can't speak to that

BALLSS

IMHO, if you can find a source to bore a stock to 52...or 54mm (neither require intake porting) that is a way more plug & play solution. Back in the day David Kudos did them, mine, but IDK who does them now.

Aftermarket TB's "often" need some form of attention to get idle right, especially on camed motors. Doing the "drill" mod is, IMHO, better than doing the slot the TPS holes and clock it bring TPS in line with the new larger TB. You do need the ability to read IAC counts to determine how big a hole to drill. Stock TB hole is 1/8". Generally a 1/64" to 3/64" larger hole does it....but never blindly drill the hole without being able to read IAC counts. 1/64" increase makes a good measurable difference so drill in 1/64" increments…..there is no way to "un do" a larger hole....well putting in a small sleeve would be one possibility if you did.

SS RRR

iTrader: (2)

If deciding to port it, please take the manifold off first, and when done, either tank it or blow it out with compressed air.

350 groundpounder

iTrader: (5)

Or you can buy my Lloyd Elliot ported intake from me! Bores opened to 58mm and the whole intake is fully ported.

atlantadan

FWIW - it is fairly simple to port the intake out yourself. As SS RRR said, take it off, grind it, and then rinse that thing out. I used a dremel and a carbide bit. Took a long time, so be patient, but in the end it worked out perfectly. I ran a Holley 58mm and now I have a TPiS 58mm. Neither needed any sort of acrobatics to get running correctly. I already had the slotted TPS so clocking it according to the IAC counts was cake.

It must be tuned for it though or you may burn out your transmission.

TheUrbz

Second time ive seen this. Can someone give me a TL;DR how this happens with a new TB? i understand the reason for slotting to get the correct IAC values. just curious about the other part.

atlantadan

If you don't adjust the line pressure, the shifts will be way soft and fry out the clutch pack. The transmission scales shift firmness partially according to TPS. So with the stock TB, (and I am pulling these % out of my ***) - at 5% on the TPS you may have been at 1000 RPM's. Now with the larger TB, its flowing more air (and fuel) so at 5% the RPM's are at 1500. Your transmission will still shift like its at 1000 RPM. Meaning it will have a lower line pressure (softer shifts and less clutch holding power) at the shift than it should because the RPM's are higher at the stated TPS.

....I think.... someone will come along and correct me if I am wrong...

When I installed the Holley, I thought I could go without it because I'd read elsewhere where some folks didn't make any adjustments to the line pressure tables. Within 300' of my house, I learned how incredibly wrong that decision was.

TheUrbz

bout to say, yall were mentioning it as if it could be overlooked, but if its in relation wouldnt someone immediately feel that? "naw, that jerk is fine, it does that sometimes"