hazmatic Posted June 18, 2003 Report Share Posted June 18, 2003 i plan on doin a 2.8 t0 3.1 conversion but i wuz readon on a site givin dif throttle body bores n shit n i can safley bore my throttle body so it will take 3.2l how much gain woukd i see?? and if u need ill give u the link to the site Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted June 18, 2003 Report Share Posted June 18, 2003 Boring the TB wont give you more displacement, cuz the TB doesnt displace anything. The 2.8 and 3.1L have the same TB. There is a 62mm (stock is 52mm) diameter TB on the net somewhere Robby Quote Link to comment Share on other sites More sharing options...
mdelorie Posted June 18, 2003 Report Share Posted June 18, 2003 Ummm, correct me if I'm wrong, insane, or otherwise incapable. But I don't think boring out your throttle body will increase your engine displacement. Are you thinking instead of rebuilding the 3.1 and boring it over to 3.2 litres? In which case, you bore out the cylinders themselves. Quote Link to comment Share on other sites More sharing options...
phantomFE3 Posted June 18, 2003 Report Share Posted June 18, 2003 after you bore out your throttle body to make your 3.1 into a 3.1 why not RE-port and polish your headers and manifolds, since there might be more carbon build up on them Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted June 18, 2003 Report Share Posted June 18, 2003 after you bore out your throttle body to make your 3.1 into a 3.1 why not RE-port and polish your headers and manifolds, since there might be more carbon build up on them yeah, port and polish the coolant passages, Im sure that'll add HP too Robby Quote Link to comment Share on other sites More sharing options...
hazmatic Posted June 18, 2003 Author Report Share Posted June 18, 2003 oh im sorry guys it was talkin bout the cylinders i read it all wrong so again back to my guestion how much gain would i see?? the site i got the info from is http://www.60degreev6.com/members/gpxss/ and it also has the 62mm throttle body thing robby talked bout but im not intersted in that right now Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted June 18, 2003 Report Share Posted June 18, 2003 If you ONLY bore it out, you wont see that much. Boring is best complimented by port/polished heads, cam, rockers, all that stuff Robby Quote Link to comment Share on other sites More sharing options...
hazmatic Posted June 18, 2003 Author Report Share Posted June 18, 2003 with out the port polish wut kind of gain would i see from goin 3.1 to 3.2?? but when i re build the engine i do plan on port polish n neotha shit ur surpose to im startin to save my money now n im findin part n ordin them i wanna get the best and aftermarket shit if possable i plan on rebuildin the hole thin wit new shit if i caqn find it afta i get all the parts ill bring it to the shop n start workin on it Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted June 18, 2003 Report Share Posted June 18, 2003 with just the boring out, I would say 5-10HP JMO Robby Quote Link to comment Share on other sites More sharing options...
91GranSport Posted June 18, 2003 Report Share Posted June 18, 2003 You won't gain that much from a larger throttle body. For example, on the LS1 you can get a larger throttle body for around $300 that'll only bring up the horsepower by 10-15. On 345HP, an extra 15HP isn't much considering you're paying $300 for it. It'd be even worse on a smaller displacement engine that requires less air. i plan on doin a 2.8 t0 3.1 conversion but i wuz readon on a site givin dif throttle body bores n shit n i can safley bore my throttle body so it will take 3.2l how much gain woukd i see?? and if u need ill give u the link to the site Quote Link to comment Share on other sites More sharing options...
91GranSport Posted June 18, 2003 Report Share Posted June 18, 2003 after you bore out your throttle body to make your 3.1 into a 3.1 why not RE-port and polish your headers and manifolds, since there might be more carbon build up on them yeah, port and polish the coolant passages, Im sure that'll add HP too Robby Quote Link to comment Share on other sites More sharing options...
91GranSport Posted June 18, 2003 Report Share Posted June 18, 2003 Okay, let's keep this simple. I'm assuming you're not made of money, so let's say you're on a tight budget. For you to port and polish your cylinder heads yourself, it'd probably cost very little. However, porting and polishing cylinder heads is best left to professional, especially when you're dealing with aluminum cylinder heads. It's easy to break into a water jacket when you're going nuts and you can warp aluminum if you're not careful. And if you go the route of paying a professional to port and polish your cylinder heads, it would be quite expensive considering the amount of power you'd gain is minimal unless you have performance roller rockers, pushrods, pistons, camshaft, etc. You see, all this shit works hand in hand so improving one thing won't do much unless you improve all of the things. It's like installing high performance pistons. If you install high performance pistons and leave the rest of the engine stock, you won't see the true potential of those pistons until you start modifying the rest of your engine. Which in turn will be very expensive. There isn't a whole lot available for either the 2.8 MPFI, 3.1 MPFI or 3100. What I would recommend is swapping an L36 or an L67 like you mentioned before. That way you have a bulletproof engine and you have 205HP. At the same time swap a tranny, either a 4T60 for the L36 or the 4T65-E/HD for the L67. Believe me, once you have a 3800 you will never want to go back to any other V-6 engine in the W-Body. I only have the 3800 TPI, but personally I think that's better than any 2.8 MPFI, 3.1 MPFI, 3100 or even the 3.4L Twin Cam. It's nearly as bulletproof as the L36, and despite the high mileage it's very low maintenance and it has gobs of torque. You can always go that route as well, a 3800 TPI with a 4T60 like in my '91 Regal GS is a very good performer. Like I mentioned, doing the engine swap you mentioned being interested in is far better than wasting your time and money on useless little things such porting and polishing. A stock non-modifed 3800 or L36 is far more powerful than any of those other engines with modifications, unless it's a turbo 3.1 MPFI. By the way, I don't want to step on anyone's toes if there are owners out there of the 2.8 MPFI, 3.1 MPFI, 3100 or 3.4L Twin Cam. I'm just speaking of experience as my first W-Body had a 3.1 MPFI, and that is nowhere near as powerful as my 3800 TPI. with out the port polish wut kind of gain would i see from goin 3.1 to 3.2?? but when i re build the engine i do plan on port polish n neotha shit ur surpose to im startin to save my money now n im findin part n ordin them i wanna get the best and aftermarket shit if possable i plan on rebuildin the hole thin wit new shit if i caqn find it afta i get all the parts ill bring it to the shop n start workin on it Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted June 18, 2003 Report Share Posted June 18, 2003 No, I completely agree. You cant just do one mod (sorta like I did my rockers, lol), and expect a lot of power. I do think that a 3.1L that has been gone through and rebuilt with performance parts, and built for performance is a good motor, even if its n/a. However, it is very expensive. But stuff is made to rebuild the entire motor with good parts. Port/polish on heads isnt that bad from a professional. I have heard $300-400 for both heads. Thats not too bad, considering what all is involved, but if you only do that, your not going to see much. I do plan on (someday in the distant future), going through my entire motor and rebuilding it. Thats why Im sorta nickel and diming performance stuff, like the rockers. Rebuilding a motor is VERY involved, and requires special tools, a lot of know how, and a shit ton of patience. If you just want to go faster, swap in a L67. If you really want to rebuild it, rebuild it, but do it right Robby Quote Link to comment Share on other sites More sharing options...
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