what is so bad about gen ii engines?

[SwiftDrift]

many go with 3x00s, some with the old iron heads, but ya dont see like any LH0s being cammed or anything, wasnt the turbo mclaren 3.1 basically an LH0?? how come no one swaps the heads from these to a gen 1? it seems like people figure--if they are going to swap, why not just use the 3500 top end? they cant be that bad.

[1988GTU]

Rather have an engine with potential than create and to have it.

[Guest]

it seems like people figure--if they are going to swap, why not just use the 3500 top end? they cant be that bad.

That's exactly what they think.

If you're going to go through all of the same work, why not put the best you can on/in the engine?

The heads on the 3.1T are no different than the N/A 2.8 and 3.1 of the same generation. Some claim small differences, that would prove to be negligible at best.

[caffeine]

The gen II intakes are very restrictive compared to the 3x00 intakes. Id say that's the major limitation. When it comes to cams you can basically use anything that works in a Gen I.

There just isn't really any advantages over Gen III except that you can use a Gen I oil pan. Compression ratio is also lower in the Gen IIs Iirc.

[Guest]

Gen II in stock form were rated at 8.9:1 (N/A) and 8.8:1 (turbo).

[SwiftDrift]

so the gen i and gen ii's are both just as shitty? so why did gm even bother going aluminum and using canted valves?

[caffeine]

The Gen II has a few nice improvements like the aluminum heads which are still better than the irons and DIS ignition is much nicer than the old dizzy setup.

But if you're going to use the Gen III heads there's no advantages really over a Gen III block which has a roller cam and better oiling system.

[SwiftDrift]

yeah i know, the gen IIIs rock, but some people build the iron heads up still, so its just odd how someone will build the ancient iron heads and the outstanding gen IIIs up yet the gen II is just chopped liver lol

[caffeine]

Building the iron heads for N/A is really pointless if Gen III is an option. They will simply never match up performance wise.

The reasons I see for people using iron heads is typically to
- avoid having to do a hybrid swap
- keep the stock look
- avoid any wiring

When you think about it, the vast majority who use iron heads are using them because that's what their vehicles came with. If you have a front engine, RWD vehicle that came with an iron head engine, a Gen II swap is the same amount of work as a Gen III swap. So why would anyone bother?

You'll probably see more people sticking with the Gen IIs in the cars that they were available in.

[SwiftDrift]

i almost want to build one just because no one bothers XD but ya makes sense. i just hate to see any 60 degree go to waste.

[geoffinbc]

There are 2 camps most drivers fall in. FWD Gen II owners and RWD which are all iron head. When you want more power on a FWD vehicle you jump right to a 3X00 because it is basically a bolt in and the gains are great for little cash. I did a 3400 swap with a friend into his 90 Z24 and the swap was very easy and it made that old girl into a pretty quick car. The RWD guys like me sometime swap up to a 3X00. It is a nice swap but for a lot of us it takes too much time and a lot of parts purchasing. It is just SO EASY to swap in a 3.4L F-Body motor or a GM Crate. You can start on Friday after work and drive back to work on Monday. The stock EFI or carb will run the motor and the swap is unnoticeable to the untrained eye which helps in places like California. Heads don't get swapped much because none of the RWD intake manifolds will bolt to the aluminum heads. So you either stick with the old iron and do what you can with it or take the leap up to a 3X00.

[robertisaar]

i'd like to re-state gen2 intakes. gen2 heads aren't really bad of a starting place from what i've seen(disclaimer: i am in no way qualified to make such a statement), but the intake set is one hell of an object to try and work around/be compromised by.

so, you can either use gen2 heads and be stuck with a stock intake/port what you can or go nuts and make a fully fabricated intake......

and all of that might bring you up to the level of a small port gen3. just doesn't make sense to spend so much time and money on something that has been superceded and requires less money and work.

[SwiftDrift]

so are first and second gens about the same hp/lbs wise? or does the genII actually have noticeably more power than the gen I? i know they are both a little on the granny side of the performance spectrum, but i have limited knowledge on the gen IIs. and i want to know as much as i can about these 60*s, ive looked into the sfi motors quite a bit+the dohc, i know about the iron heads, but never really looked at the genIIs, i just figured they must be somewhat decent if they have aluminum heads and splayed valves. im probs not gonna build one, but i just dont like not knowing about something like this.

[Superdave]

The latest Iron head 3.1 (1992 Fbody) and aluminum head 3.1 (1994 Cavalier) were pretty similar in output overall.

Gen 1's are limited by the crappy head design, Gen 2's are limited mostly by the upper/lower intake design, and secondly by the casting quality of the ports (they did get better over the years).


It's always better to start off with the best foundation you can get, gen 3's requite less work to reach the same power.

[SwiftDrift]

i wish i could get side by side shots of a geniii and a genii head, i know they are different but i just wanted to see if the geniii was based off of that design. i like looking at older and newer stuff and seeing what got changed over time. do the genii heads share some of the same casting/dimensions as the sfi heads?