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Supra mentality has been terrible over the years from what i seen and why they got the bad rep for high trap speeds but no et. They always had huge singles 88mm + but the guys around me run small turbos and make big numbers. Local shop car runs a 71 mm single and made 1000whp on his supra. Footbrake class so that size actually spools quick on a supra. Another kid just finished his 76mm class supra and maxed out twin 340 lph pumps on q16 fuel through a th400. Thats gotta be 1100-1200 hp worth
It does come down to the combination and how well the compressor fits that engines characteristics. Run a big turbo on a small motor then you better turn some rpm, which requires cam and head improvements inorder to fit the compressor operating range.
I think they all do. haha And I have another question if I were to build a turbo charged 305 to say about 500HP how streetable would it be? Sorry like I said I am not very familiar with boosted engines.
Boost motors generally run smallish cams and heads sized for the rpm range like a n/a motor and are low compression. Boost adds power so you dont need as much engine power to start with, so hence the reason for less cam and smaller heads for the power goal.
It will drive like stock for the most part. Heck you could run stock motor and just add loads of boost and have stock driving car with big power. Thats ideal.
In boost however its gonna be powerful. But depending on the rpm range and spool characteristics it could be violent transition to power or a smoother one.
Once you get into wilder combos the driveability changes. Higher hp means bigger cam bigger heads more rpms and more boost.
I think they all do. haha And I have another question if I were to build a turbo charged 305 to say about 500HP how streetable would it be? Sorry like I said I am not very familiar with boosted engines.
the nice thing thing about a boosted engine is u can make really high hp with a well mannered stockish driving engine
my twin turbo iroc besdies the cam drives just like a stock 89 tpi iroc , having some issues now cause i have a stock converter in it with a backup trans so i stall it now and then, but when the proper pieces are in it u could drive it anywere without worrys
the nice thing thing about a boosted engine is u can make really high hp with a well mannered stockish driving engine
my twin turbo iroc besdies the cam drives just like a stock 89 tpi iroc , having some issues now cause i have a stock converter in it with a backup trans so i stall it now and then, but when the proper pieces are in it u could drive it anywere without worrys
Sweet, so if I upgrade the tranny. I would be good? I would also want to replace the cylinder heads, intake and cam so it could take that air flow right?
depending on how much power u make the stock 700r4 prolly wont live long ive blown up 2 built 700's so far in my car, and the only reason its hard to drive with the converter in it now is cause i have a cam that wants more rpm at cruise . with the stock converter and 2:73 rear gear my cruise rpms are very low
a bone stock 350 with 7 psi of boost the 700 should survive a good bit if u dont thrash on the thing all the time , at minum u need a good trans cooler and a transgo or on of dana at probuilts shift kits
They still break if you beat on them. My friend has been through a complete G force upgraded T5 with a new fabbed case and everything and still breaks parts on a 11 second, mid high 400's whp mercury capri turbo 2.3
So if I had a completely stock 305 I could just turbo charge it to about 500HP with out any other changes? Or what changes would I have to make?
stock 305ci came with up to 215HP and 295 ft / lbs
500/215 = 2.3 which becomes 20PSI of boost
That is 295 * 2.3 = 696 ft / lbs
So if you ran 20 PSI on the best stock 305ci then you would have 500hp and 700 ft/lbs of torque. My stock700R4 fresh local shop rebuild croaked with 10K miles on it with a stock 305ci and 10 PSI of boost. The 4L60E in it now is built more and has last for 12K miles so far.
With the stock 305ci 9.3 or 9.5 compression ratio, you need good gas for 20 PSI of boost.
They still break if you beat on them. My friend has been through a complete G force upgraded T5 with a new fabbed case and everything and still breaks parts on a 11 second, mid high 400's whp mercury capri turbo 2.3
Do not go T5.
Good built 700R4 will handle 500 whp all day long
I DO NOT BELIEVE that for a minute, well it depends on what car the 700r4 is in. I was grenading them, splitting cases, and stripping case lugs off the case at just under 400 RWHP.
That being said the high mileage, mostly stock replacement parts 425 HP 312 with factory 4 bolt mains and arp studs in my brothers 1980 Vette has already had about 20 full 15 lbs bottles run through it on a 250 HP shot using a progressive controller. It is cranking out just over 550 @ 5,800 to the tires on a Mustang Dyno through a 2,500 stalled TH400 on spray while making over 600 ft/lbs @ 3,500. Nitrous shuts off at 5,800 and the MSD revlimiter kicks in at 6,500. Total timing is 22* on nitrous or about 10* retarded from NA, 3 heat ranges cooler copper plugs, and the WOT air/fuel ratio is in the mid 11s. We modified a new stock replacement steel tank for a rear sump and run dual holley blue pumps in parallel with a pair of bypass regulators. We have it set up for the 355 that is going in its place. The car really needs a solid 9" ford rear end, to be tubbed, and a cage installed. At just over 2,600 lbs its quick on motor alone and down right scary on N20.
The car is currently undergoing some body work from a small accident that mangled the front clip but did not hurt the chassis at all.
The engine pic is while swapping on long tubes, single plane victor jr, 830 vacuum secondary carb, removing the stock fuel system and installing the new tank, full 2.5" dual exhaust with X pipe, and installing the N20 as well as the MSD. We also built a custom E-fan setup, removed the powerglide for the TH400 and had a custom converter built for the power and vehicle weight.
The "BIG" motor is ready to go when the 305 goes, which may be a long time to come. It is a 9.5:1 355, fully forged and blueprinted with a nice nitrous grind hydraulic roller cam, aftermarket dart heads with worked 215cc intake runners, 2.08/1.60" valves, and an edelbrock air gap dual 4 bbl intake with two 500 cfm edelbrocks. It will have a pair of spray plates. We are shooting for 700 HP on a 200 hp nitrous hit.
Hmm so everyone agree the T56 is the way to go then?
I would go with a built 200R4 before I go T56. You are simply not out launching a stalled 200R4 with a trans brake, nor are you pulling one on the highway because the 200R4 doesn't have fourth gear lock out, that is just not happening. Be wise with your choice before you jump on the bandwagon...
I DO NOT BELIEVE that for a minute, well it depends on what car the 700r4 is in. I was grenading them, splitting cases, and stripping case lugs off the case at just under 400 RWHP.
Probably didnt have a good built one then lol. I never had a problem with mine, 400 whp 383 plus 150 shot. Mid 10 sec car, 1.4x 60 fts. 4l60e's are very similar and are holding 8 second vettes on a rebuild that costs 5 grand.
Depends what you throw into them for parts they shouldnt be breaking
I would go with a built 200R4 before I go T56. You are simply not out launching a stalled 200R4 with a trans brake, nor are you pulling one on the highway because the 200R4 doesn't have fourth gear lock out, that is just not happening. Be wise with your choice before you jump on the bandwagon...
I would say if he is not afraid of electronics an obd2 swap with a LS1 0411 pcm and a 4L80e. For the money saved and the strength he adds he can build se extra hp to compensate for the weight and the parasitic loss of the 4L80e.
Probably didnt have a good built one then lol. I never had a problem with mine, 400 whp 383 plus 150 shot. Mid 10 sec car, 1.4x 60 fts. 4l60e's are very similar and are holding 8 second vettes on a rebuild that costs 5 grand.
Depends what you throw into them for parts they shouldnt be breaking
I was breaking the factory cases after upgrading the geartrain.
A $2,000 near stock rebuild 4L80E with a shift kit will handle that power and more. If one spends a little extra they can get a lower ratio planetary set that gives the 80e almost identical ratios to a 2004r except much beefier.
Yeah they can hold power but more expensive to do and huge trannies. Fitment is alittle concern but more importantly, need a crossmember which no one makes that i know of.
411 ecm swap isnt cheap and efi connection isnt doin thirdgen harnesses at the moment. You'd have to build one yourself which is very time consuming. Then you'd need 600$ software to tune or spend 500-800$ for dyno tune sessions with a pro. If you didnt do 411 ecm you would need full manual valvebody or the trans controller which isnt that cheap either but still a good option
Pros and cons to both. If not track racing car constantly then i would try 700r4 build for up to 500whp. Much more you will want to consider something else
I would say if he is not afraid of electronics an obd2 swap...
Bingo, I was targeting the '82 Z28 in his description, eliminating the need for an e-trans. 200R4's, when properly built, will take whatever you can throw at them. They accept a trans brake, they fit no problem, and when properly stalled they will catapult even a modestly built 3.8 Turbo engine deep into the 1.4x sixty foot land...
No need for the OBD2 411 ECM. The GM 1994-95 truck OBD1 ECM will control the 4L60E and 4L80E trans and MPFI or TBI injection.
I have been running OBD1 ECM for years with hi-z injector TPI and 4L60E and it works great.
Nice thing about the E-trans is you can play with line pressure for power adders.
No need for the OBD2 411 ECM. The GM 1994-95 truck OBD1 ECM will control the 4L60E and 4L80E trans and MPFI or TBI injection.
I have been running OBD1 ECM for years with hi-z injector TPI and 4L60E and it works great.
Nice thing about the E-trans is you can play with line pressure for power adders.
Stupid question, have you ever done a "trans only" one? I have an early box that I'm looking at getting a clue on, and have an early ECU for it as well. I've read it can be done and has been done, just working up the nerve to try it some time.
In regards to the crossmember, no one made one for an Astro van either; mine has an 80E in it. It's simply called a MIG welder and a chop saw. Not only that but the Camaro installs have been done before and are documented at least in fourth gens which should put you into the ball park. I would guess you'd have a ton less to figure out than I did. Core 80Es are getting cheaper every day too, I can get an early one from the yard for $200 with the core charge included.
There is an entry level 4L80E controller out there for $400 or so. I wish I'd have done that I did the Megashift instead. Overall not impressed. The Megasquirt II integration features are great, but the maturity of the product and documentation is not there.
It's foolish to build an engine like this without thinking about the power train. Even the engine in a Syclone uses a stock cam and stock TBI heads but makes 360 ft-lbs. As junk hit on even with a basic stock or lightly modded 305 you're talking big torque And that breaks stuff.
On the topic of Supras, some guys run the huge 114mm or whatever turbos to make big dyno #s. Some people like to actually go fast though. My buddy had a 2JZ with a 66, made 690hp at the wheels. Saw it on the dyno myself. He pulled about 16 inches of vacuum too. His cams were something like 229@.050, that's a ton of vacuum for a little 3L engine. Shows what technology does. Just like racing a N/A car it's ALL about "area under the curve." If you up your turbo size and ultimately reduce your area under the curve you'll have poor performance.
Junk:I thought dual cat cars had 235, and that Vortec 305s had 235 as well. Then again the typical 305 is under cammed, under valvetrained, under intaked and probably slightly under headed (but not nearly as bad as everyone makes out.) You add a few bolt ons/do some porting 500hp becomes a lot easier to attain. You may bump the RPMs up a bit to do it but I wouldn't think horribly considering the low peak HP RPM these engines typically have stock.
Supra mentality has been terrible over the years from what i seen and why they got the bad rep for high trap speeds but no et...
Definitely not what I was referring to when I credited them with the Turbo Buick guys, I only conversed with real enthusiasts, not the youtube guys looking for glory. The bore and stroke of the 2JZ is essentially the same as the 305, but their cylinder heads are obviously not as restricted as the 305 cylinder heads which give up the ghost a lot sooner in RPM. So the question soon becomes, how do you get the 305 engine to breath close to, or just as good as the 2JZ, while remaining effective, with such a restrictive combustion chamber. This is where Turbo Buick intelligence comes into play...
I dont think its rocket science, just takes a good port design which nobody really messes with small bore motors. Why should they? 350's are available. They have been around for 60 yrs lol. Not like you cant find one.
If you could find someone to take a raw casting and cut the chamber and port with the idea in mind that its going to be on a 3.76 bore or whatever, then you would see fairly stout systems. Cut the valves so that a decent size intake valve can be used yet not be shrouded. Cut the port for ideal velocity profile and area for closer to 7k rpms. Throw in forged rotator and you'd surely see some very strong 305's.
No one does it tho, except for maybe a rare stock eliminator type build but they use very carefully crafted stock castings and ports, possibly hiding mild port work and valve jobs . If you spent the time on good castings it would make even better power
Hmm so everyone agree the T56 is the way to go then?
It really depends on how you plan to use the car, Most of the people answering your questions are drag racers,
The T56 doe has it week point over a certain HP, depending on what it came out of,
I dont think its rocket science, just takes a good port design which nobody really messes with small bore motors. Why should they? 350's are available. They have been around for 60 yrs lol. Not like you cant find one.
If you could find someone to take a raw casting and cut the chamber and port with the idea in mind that its going to be on a 3.76 bore or whatever, then you would see fairly stout systems. Cut the valves so that a decent size intake valve can be used yet not be shrouded. Cut the port for ideal velocity profile and area for closer to 7k rpms. Throw in forged rotator and you'd surely see some very strong 305's.
No one does it tho, except for maybe a rare stock eliminator type build but they use very carefully crafted stock castings and ports, possibly hiding mild port work and valve jobs . If you spent the time on good castings it would make even better power
I bet the 2.00/1.55 valves and 210cc intake ports of the gm fastburn heads could be well utilized by a turbo 305.
I bet the 2.00/1.55 valves and 210cc intake ports of the gm fastburn heads could be well utilized by a turbo 305.
I was actually thinking of doin something like that. I have seen a 383 use mild cleaned up port fastburns and make something like 580's hp with a hyd roller that wasnt huge. Only 230 deg. This motor was very stout so the heads can support the power, its just getting a 305 to utilize it via rpm. 7500+ would be fun and sound like an old dz302
Stupid question, have you ever done a "trans only" one? I have an early box that I'm looking at getting a clue on, and have an early ECU for it as well. I've read it can be done and has been done, just working up the nerve to try it some time.
Never tried trans only. Using once ECM for both engine and trans was a better option for me.
Originally Posted by Drac0nic
I thought dual cat cars had 235, and that Vortec 305s had 235 as well. Then again the typical 305 is under cammed, under valvetrained, under intaked and probably slightly under headed (but not nearly as bad as everyone makes out.) You add a few bolt ons/do some porting 500hp becomes a lot easier to attain. You may bump the RPMs up a bit to do it but I wouldn't think horribly considering the low peak HP RPM these engines typically have stock.
I think the TPI 305ci was up to 215HP, and the Vortec 305ci went to 220HP but I could be wrong. All had lame cams. I think the cam in mine is .350 lift. The good news is that the tiny lobe should live forever. Bad news is that it takes 10PSI to make 350HP.
305 talk is great if ya already have one in the vehicle. Best bang for the buck is 350 vortec for $100 from craigslist. Put a regrind cam, china intake, and turbo on it. When my 305 croaks, a JY or CL 350 vortec will replace it. If an LM7 had provisions for dizzy I would go with that. I still like GM OBD1 ECMs over the MS-II and OBD2 ECMs.
I would say if he is not afraid of electronics an obd2 swap with a LS1 0411 pcm and a 4L80e. For the money saved and the strength he adds he can build se extra hp to compensate for the weight and the parasitic loss of the 4L80e.
I don't want an electronics in my Camaro and I want to have a first generation small block for sure.
I don't want to build a dragster, I want to build a car with more of a Corvette feel. So are there really any good manual transmissions you can put in a thirdgen?
Never tried trans only. Using once ECM for both engine and trans was a better option for me.
I think the TPI 305ci was up to 215HP, and the Vortec 305ci went to 220HP but I could be wrong. All had lame cams. I think the cam in mine is .350 lift. The good news is that the tiny lobe should live forever. Bad news is that it takes 10PSI to make 350HP.
305 talk is great if ya already have one in the vehicle. Best bang for the buck is 350 vortec for $100 from craigslist. Put a regrind cam, china intake, and turbo on it. When my 305 croaks, a JY or CL 350 vortec will replace it. If an LM7 had provisions for dizzy I would go with that. I still like GM OBD1 ECMs over the MS-II and OBD2 ECMs.
Yeah, nothing like a 179/195@.050 cam to set the street and strip on fire.
Man your market must be totally different than in Chicago. I haven't seen any up here, if you have some I'll buy em all day long. My buddy was paying 2-3X that for a core with known issues as in busted ring lands.
I'm doing the MS2/Megashift route, but really thinking starting to use the OE box for at least the trans is a better route.
I don't want to build a dragster, I want to build a car with more of a Corvette feel. So are there really any good manual transmissions you can put in a thirdgen?
If you are looking for a stock manual trans the T56 is your best bet, The strongest stock one built is from the Dodge viper, It can hold up to the HP your looking for, Not all T56s are created equal. For a more direct bolt up to a sbc I would say get a 93 or 94 from a LT1 camaro or firebird. but those would need to be upgraded for 500+hp And for the cost of the trans and upgrades you may want to look at the TKO500 or TKO600. these are 5speed trans built to handle 500 to 600 hp.
Does anyone know how much horsepower a 305 block can take without dieing on you? The rotating assembly doesn't concern me because I could just buy a forged one for a 350 that would handle anything I could throw at it. I want to build a 600-800HP 305 just to do it, but would the block even be able to handle it? I know I would have to have it made into a 4 bolt with the outer bolts splayed, but even then would it be able to handle 600-800HP?
My 1991 Z/28 is in that horsepower range (blown and stroked and now with a little extra spray) with a splayed 4 bolt bottom now but I have seen an almost bone stock 305 except for vortec heads crest the 600 mark with the stock 2 bolt bottom end!
Check it out here!
This will definitely shock some people!
Watch this and this might answer the op original question, I know it's sprayed but u get an idea what a 305 can handle...
It really just comes down to the internal parts. Also, it's the way the members on this website use the English language in which everything gets misconstrued about the engine. Guys who say boosted 305's can't "make" power because of it's size are clueless, especially when the 2JZ shares a similar same bore and stroke, but with better breathing of course because of it's cylinder head. However guys who say 305's can't "make" power because of their guts are absolutely correct. Any engine with cast parts is limited to around 450-500RWHP horsepower while expecting to live for awhile, it doesn't matter if it's a 305 or 383, a cast piston is a cast piston and it can only take so much abuse. Engine size is irrelevant with boost. X amount of air and fuel will make the power you need, a dyno is a resistance measure just like boost pressure...
Mine handles that level of power! Have it built right! Balanced rotating assembly and a splayed 4 bolt main and it handles the boost that mine is subject too. It’s a sbc that is no different than a 350 bottom end wise.
Bit of a thread dredge here. That said, back in the day on Turbo Mustangs there was a guy with a Cutlass that ran 5.65s in the 1/8 with a production 400 block. That's low 9s, and at say 33-3400lbs 700 to the tire without too much issue. They are a notoriously weak block compared to even a 350 due to the siamese bores, so I would think that would be the bare minimum you'd be shooting for out of a stock 305 block with 4 bolt caps. Now then, could you get there? It's plausible IMO, but you'd be looking at a formula like getting to 1HP/CID N/A then having a well sized turbo kit and 30ish PSI.
Then again look at what people do with 4.8s these days. I wouldn't be surprised if a 305 could do it *IF* you can get the induction and valvetrain right (7K towards 8K seems to be the norm on a 4.8L that's setting records.) In that range you're talking 220-255 CID. It has a 3.78" bore and a 3.27" stroke, which is a .045 over 305.
Ls heads are far superior to the small bore sbc heads. So it be difficult to get a good head on a 305 that will support high rpm like the 4.8-5.3 turn. But something like the gm fastburn head with 1.94-2.00 valve ported some have been used on 305's and made good power. Trickflows small bore 175 head could work good to. Iron vortec 305 head ported may also work good but its iron
Splayed cap conversion would be necessary for any sort of power and rpm. A great forged crank as well. Crank flex will hurt the caps and block. Dont want that.
Then just cram boost in it, they will wake up. My stock 305 radically improved with just 7-8 psi. Who knows what it could have done if the valvesprings were upgraded to prevent float
In my case my answer to head flow was some heavily worked LT1 heads on my 305. For me it was cheap since I could do all the welding and machine work myself. Plenty of flow (over 250cfm tested on a 3.75" bore). The problem with this is even with a very mild cam that results in a 305 that really wants to turn rpm. Mine feels a lot like the stock TPI setup below about 3000rpm, and then it really starts breathing and instangly wings up to 7000.
Just reading through this whole discussion the trick really is to keep RPM down. RPM will hurt it faster than boost, even making a lot more power with the boost. I know that after making a few runs up to higher rpms mine is making some noises that are worrying me.
As far as making power with boost... why is everyone comparing them to 2JZ's? Forget that, look at the turbo 'icks, dimension wise the stock 3.8 is almost exactly a 305 with 2 cylinders lopped off of it. Follow their formulas for going fast... and go fast.
My 350 died so I bought a cheap pull out a 1pc, roller cam 305 from a pick up truck. I cleaned it, honed it, install new bearings and piston rings. Added the 350's cam, a set of stamped 1.6 rockers that had laying around and that's it.
I frequently run that 305 in Auto-X and road course events for 15-20 minutes each session with a T76 turbocharger and boosted up to 18-20psi of boost which gives out around 500rwhp+. At 15psi the 305 pulls out 425rwhp/456tq.
So far the engine is safe and sound, ready for the next event!
Around the 550-600hp AT THE CRANK mark is where things start to get risky on a factory gen1 block.
Don't watch an episode of engine masters with a 305 pumping out 2hp per cubic inch or read something out of hotrod magazine where a production block made 800HP for a dyno pull or two or a couple times down the track and think you'll be fine at those levels.
It might last beyond that 550 point, but the question becomes for how long? The main webbing and the lifter area (Which is what the main webbing is connected to and generates downward thrust against) become the weak point at those levels and you risk blowing the crank right out the bottom of the motor.
This is why on my engine making just shy of 400 at the crank that I only spray a 100 shot even though the internals could handle a bit more.
06-25-2013, 11:13 AM
My buddy had a 2JZ with a 66, made 690hp at the wheels. Saw it on the dyno myself. He pulled about 16 inches of vacuum too. His cams were something like 229@.050, that's a ton of vacuum for a little 3L engine. Shows what technology does. Just like racing a N/A car it's ALL about "area under the curve." If you up your turbo size and ultimately reduce your area under the curve you'll have poor performance.
