tazman11683 Posted November 12, 2012 Report Share Posted November 12, 2012 so i grabbed a junk yard 3.1 from a yard i have never bought anything big from got it in and had to change some stuff around motor mounts ac system sensors well i discovered that my 1991 3.1 sensors did not fit in the new motor so i did some research and to my great surprise its a 3400 bottom end with 1990 style 3.1 intake and heads motor has great vitals but has a broken quick disconnect on the coolant tube its clean broke off so i am going to have to get creative on getting it out but am pleased that its got the 3400 bottom end i have heard its stronger than the early 3.1 blocks any ideas ?? it seams way punchier than my 3.1 did Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 12, 2012 Report Share Posted November 12, 2012 how much horsepower is it going to have when its done? Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 12, 2012 Author Report Share Posted November 12, 2012 how much horsepower is it going to have when its done? idk i did not build it but after its done and tuned i will put it on a dyno and see what we get Quote Link to comment Share on other sites More sharing options...
Night Fury Posted November 12, 2012 Report Share Posted November 12, 2012 Seems like it'd be starving for air with a 3.1 intake Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 12, 2012 Author Report Share Posted November 12, 2012 Seems like it'd be starving for air with a 3.1 intake idk its verry common in the old fieros to use a 3400 bottom end with the 2.8 top end Quote Link to comment Share on other sites More sharing options...
Night Fury Posted November 12, 2012 Report Share Posted November 12, 2012 Seems pointless? Even risking knock? Am I wrong here? Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 12, 2012 Author Report Share Posted November 12, 2012 Seems pointless? Even risking knock? Am I wrong here? ya its been done hundreds of times a on fieros with great success and on several l body cars with great success Quote Link to comment Share on other sites More sharing options...
skitchin Posted November 12, 2012 Report Share Posted November 12, 2012 Smaller intake = less air = richer mixture = safer? Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 12, 2012 Report Share Posted November 12, 2012 I dont know whether to or to ... Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 well it runs great has more pep than my built 3.1 did warm idle oil pressure is at a bar above half and it has a spot to add a pulley to bypass the ac pump and use a shorter belt i am liking this Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 13, 2012 Report Share Posted November 13, 2012 Whats a "built 3.1" ? Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 gm 3400 block with a 2.8 top end done long ago and running great note that there is no distributor and all fiero 2.8's have them thats cuz its a 3400 under there and he decided to run coil packs also the 3400 bottom end is a very common swap in the 2.8 chevy s10's Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 13, 2012 Report Share Posted November 13, 2012 ok so Ill ask again.... whats a "built 3.1" Also, with the 2.8 heads intake on a 3400 bottom end, thats very low compression, not to mention your choking the motor with how small/restrictive those intakes/heads are. Your no better off then a small port 3100... Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 well mine was bored 30 over arp studded 40 pound injectors cammed modded computer tuned to the car Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 ok so Ill ask again.... whats a "built 3.1" Also, with the 2.8 heads intake on a 3400 bottom end, thats very low compression, not to mention your choking the motor with how small/restrictive those intakes/heads are. Your no better off then a small port 3100... a 3100 and a 3400 intake interchanges and as far as i have seen are the exact same Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 13, 2012 Report Share Posted November 13, 2012 There are small port and large port intakes. Completely different. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 13, 2012 Report Share Posted November 13, 2012 40 lbs injectors is overkill. And thats not exactly what I would call a "built" motor. I would call it a "cammed" motor. Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 There are small port and large port intakes. Completely different. hmm odd i have never ran into any issues running the 3400 block under the 2.8 or 3.1 top ends and chevy them selves use the 3400 camaro block in 2.8 s10's as a upgrade crate motor and this junk yard motor has 80k on it this way and runs perfect i have built many 60 degree motors and have been a mechanic for 12 years at a shop and we use the 3400 block under 2.8 top ends all the time as upgrades as gm service says to do so Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 (edited) i have seen what my motor builds can do my fiero 3400 ran awesome and was faster than my buddies northstar car all day long its all in how u tune them mine are tuned on the go over my laptop and are fully adjustable on the go i have seen my olds at 150 mph with my built 3.1 so did my passenger that doubted me and so did the pos subby that tried to pass me Edited November 13, 2012 by tazman11683 Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 13, 2012 Report Share Posted November 13, 2012 why not just swap in a 3400 with a 3400 top end? Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 13, 2012 Report Share Posted November 13, 2012 hmm odd i have never ran into any issues running the 3400 block under the 2.8 or 3.1 top ends and chevy them selves use the 3400 camaro block in 2.8 s10's as a upgrade crate motor and this junk yard motor has 80k on it this way and runs perfect i have built many 60 degree motors and have been a mechanic for 12 years at a shop and we use the 3400 block under 2.8 top ends all the time as upgrades as gm service says to do so Thats because the 2.8 heads themselves will bolt to the block, so you naturally used the matching intakes. Try bolting 3100/3400 intakes to those heads. Wont happen. Iron heads will only bolt to the 2.8/3.1 intakes. While the aluminum heads are for the 3100/3400/3500 intakes. Thats why you never had an issue. But even the 3400, several generations of that as well. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 13, 2012 Report Share Posted November 13, 2012 why not just swap in a 3400 with a 3400 top end? Thats kinda what I was thinking. Unless you wanted it to look stock, but then again with the iron heads on there, your not gaining anything in performance either so it really makes no sense at all... least not to me. Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 the 3400 does not look right in them and gm literally sales a shortblock to be used with the 3.1 top end Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 13, 2012 Report Share Posted November 13, 2012 It may not look right, but its more power Quote Link to comment Share on other sites More sharing options...
tazman11683 Posted November 13, 2012 Author Report Share Posted November 13, 2012 ya i just looked that up the 3.1 top end on the 3400 block is only 18 hp less than the complete 3400 not enough of a gain to me i can make that up easy in tuning Quote Link to comment Share on other sites More sharing options...
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