gnx turbo v6 vs 305v8 questions

[creamgorilla]

I've always wondered why the v6 with the turbo is so much more awesome than the 305 v8. Its obviously the turbo but why is the 305 with a turbo not ripping up everything like the v6? Most people upgrade to the 350 but I'm just curious if there is any hope for the 305?

[GNon18s]

EI think a 305 with good heads and a nice fuel injection setup would run great. Add a turbo to the mix it would be even better. The cubic inch isnt as important as a lot of people think. My 122 cubic inch Mitsubishi motor made more power than my Buick GN turbo v6 (231 cubic inch). My GN made more power than my LS6 corvette (347 cubic inch). It all depends on the induction, Turbo/heads/injection ect. If I remember correctly that Land speed car owned by George Poteet makes @ 2,000hp and is only 300 cubic inch.

[WS6]

I honestly don't know of any 305s with forced induction so I can't comment on that aspect. However, the biggest issues 305s have is poor aftermarket support for cylinder heads that are worth a damn. The reason being is the bore size of the engine greatly restricts what valves you can put in the motor. There's just no reason to support a 305 with performance parts. It's a lot like 307s, there's no reason to offer the parts.

I have no doubt that a 4 valve head would do just fine on a 305 if they existed. That would allow more air flow into the combustion chamber.

[XLexusTech]

I honestly don't know of any 305s with forced induction so I can't comment on that aspect. However, the biggest issues 305s have is poor aftermarket support for cylinder heads that are worth a damn. The reason being is the bore size of the engine greatly restricts what valves you can put in the motor. There's just no reason to support a 305 with performance parts. It's a lot like 307s, there's no reason to offer the parts.

I have no doubt that a 4 valve head would do just fine on a 305 if they existed. That would allow more air flow into the combustion chamber.

+1....
Nice answer Trey...!

[LS1-IROC]

I honestly don't know of any 305s with forced induction so I can't comment on that aspect. However, the biggest issues 305s have is poor aftermarket support for cylinder heads that are worth a damn. The reason being is the bore size of the engine greatly restricts what valves you can put in the motor. There's just no reason to support a 305 with performance parts. It's a lot like 307s, there's no reason to offer the parts.

I have no doubt that a 4 valve head would do just fine on a 305 if they existed. That would allow more air flow into the combustion chamber.

Pretty much sums it up...the bore size is too small for an adequate valve.

[GNon18s]

The stock Grand National valves are only 1.71" and 1.5". I havent researched how much bigger valves you can get in an aftermarket 305 head but i know its bigger than that. Plus it would be 8 sets of valves intsead of only 6 sets in the GN motor. Then you would run a performance oriented valve like a Ferrea or whatever and it would flow better than a stock type valve for any given size.

[SR71]

no. there is no hope for the 305.

why would anyone waste money on a 305 when you can do a 350 cheaper? and if you already have the 305, 350 cores are cheap and plentiful.

[KacyZ28]

This is why most people don't http://www.theturboforums.com/threads/305196-single-turbo-305-dyno-results

[GNon18s]

This is why most people don't http://www.theturboforums.com/threads/305196-single-turbo-305-dyno-resultsNot wanting to be a smart a$$, but what does this link show exactly? That a guy turbo'd a stock 305 and hurt the stock cast pistons?

[WS6]

I'd say because with 10 psi the engine only put 300/300 to the wheels. That's pretty weak.

By way of comparison, 10 psi in a stock LS1 will put you near or over 500 rwhp. 10 psi in a stock LT1 will put you over 400 rwhp and approaching 500 rwhp with a little port and cam work.

[Steve Chryssos]

The 305 has always suffered from small valves that are shrouded by the cylinder walls and chambers. A company I worked for, World Products, made a casting with narrow valve centerlines and tweaked that moved the valves away from the cylinder walls and accommodated a 1.94 x 1.50 valve set without the shrouding. They worked extremely well, but relative to small displacement, the end result was still low output.

I have not worked at World in well over a decade, so I do not know if the product still exists. Ultimately though, it has always been more effective to yank the 305 and replace it with something else.

[Randy67]

I honestly don't know of any 305s with forced induction so I can't comment on that aspect. However, the biggest issues 305s have is poor aftermarket support for cylinder heads that are worth a damn. The reason being is the bore size of the engine greatly restricts what valves you can put in the motor. There's just no reason to support a 305 with performance parts. It's a lot like 307s, there's no reason to offer the parts.

I have no doubt that a 4 valve head would do just fine on a 305 if they existed. That would allow more air flow into the combustion chamber.

Great answer. A good head designed for a 305 could make it a good engine. Consider this, the new Ford 5.0 has a smaller bore and longer stroke than a 305, but performs much better with its better head design (and newer technology). Makes you wonder what would a 305 do with a 4-valve head. But when money comes into play, it just makes sense to run a 350 instead.

[cornfedbill]

Yes, it is the bore size and the way it restricts the valve size and shrouds the valves. Two flow restrictors.

You are correct, a turbo can push more air, but a 350 turbo will breath much better than an equivalent 305.

The advantage of a bigger bore and its affect on breathing is why I am running a 377. The 4.155" bore breathes even better than the 4" bore 350. I like the shorter 3.48" stroke because I think it revs better and gave me the right compression ratio with near zero deck height flat tops.

[UNGN]

The original Turbo V6 in the GN was "awesome", because anybody with the slightest amount of internet/automotive skill back in the mid 1990's could run a low 12 with one with minimal (and very cheap) mods, while $1000's of dollars in typical performance "bolt ons", luck and perfect air netted a 13.9 out of a 305.

It wasn't a fluke thing or involved a ringer car... pretty much every '86-87 Buick turbo could run low 12's@110+ if you just did a few mods that were posted on the internet... you just had to follow the recipe (even with the stock, untouched motor, stock turbo, injectors, intercooler, headers, rear axles, virtually every thing still stock) and add race gas... and back in the mid 1990's only race cars and $80K+ sports cars ran that fast.

As far as head flow goes, nothing sucks worse than the stock flow from on a 3.8L V6 (Ok, a 301 pontiac is worse, but only a little) The Buick heads have tiny ports made even worse by casting flash and slag. Compressed air and intercooling can do wonders with bad head flow and combined with good head flow is downright amazing... which is why neither is the preferred starting point for anything in the year 2012, since junkyards are overflowing with LS1 stuff.

Buick had amazing results 25+ years ago turbocharging/intercooling something bad. Imagine the results you could have if you turbocharged/intercooled something good.

[MonzaRacer]

305 is **** block with even worse heads thats why. Only one block has worse bore and that was the 267 at 3.5 in bore.
305 only had one thing going ti had enough torque to pull heavier cars around till the 4cyl/v6 engines got developed enough.
Turbo any engine that is strong enough and it will take the performance world by storm. Buick with several guys who learned, developed and experimented with turbos, Banks, Rayhall, etc and they took the one V6 b uilt from a tough free breathing design,,the post nail head Buick V6. Add a turbo and the Buick was a tough customer.
Ever see the one turbo V8 GM built, made like 1000 hp on near stock block.It was a Buick built back in late 60s, early 70s, saw it in a book.
Go look at turboforums.com, search the forum for The Grenade, proof that junk can run and turbos make it happen.
you can turbo a lawn mower if you have turbo small enough. It makes little engine feel and act bigger.
Bad thing is reason you throw out a 305 I have no clue because a larger bore engine has better burn characteristics, biggest reason 305 was developed was because old tech emissions couldnt keep 350s as clean and less cubic engines use less fuel. Small cylinders make less NOX emissions as those are supposed to be bad,,yet we add the basic compounds to ground to grow crops.
Un burned fuel is burnt by cat converters and also convert CO or carbon monoxide into carbon dioxide.
But why would weak, thin cat, under flow headed, small bore ba$ tard engines get little respect, because they were a crap design to start, take all parts install in 307 block, you get better idea engine over 305.
80s and 90s proved small chamber high flow heads do work and have better emissions and power.