So, I stopped into a local body/restoration shop today. Just to shoot the breeze. As the owner and I are chatting, it comes up that I am putting the turbo on my Nova. He then offers to engine dyno it. FOR FREE! How do you pass up on that! So I guess I need to get on my horse and build the 250 with the goal of 20lbs! Where do I begin!
One of my friend's does some kind of auto-cross/GP racing and invited me to their chassis dyno day (6 hours from here) with promise I could stick my Firebird on the chassis dyno a few times during the day while they were making changes to their engine. I was ready to load up with two different cams, in cam housings, and head out there to make a three cam, plus cam timing adjustments, dyno day of it but my work schedule didn't cooperate :'( They fought gremlins the whole day, so I've been waiting patiently for a "re-schedule" and crossing my fingers it lines up on my days off.
I guess my debate now, do I throw the turbo on my current engine and patiently build the 250 turbo engine or do I go all in on the 250 and leave the turbo off my car until the new engine is built.
The first thing to go on a stock engine will be pistons. How long is the offer good for. It would be a shame to use the free dyno offer on engine you had not built for the turbo. The build depends on what you will use the car for, really use the car for. A good street build would not have to be a really expensive one. A full blown race motor is another deal.
"I wonder if God created man because he was disappointed in the monkey?" Mark Twain
Yeah, you would really hate to use up this favor on a less than worthy build. A well planned and better funded built will take longer for sure. Just make sure the offer will still stand if it takes a year or so to build the engine you truly want.
Get a spare engine and see how much boost a stock 250 will take before blowing apart.
Think of the fun you could have!
Snowman has seen 20+ psi or so when he first got his stock long block turbocharged. First engine. He then settled on 15 psi, but had no idea it was detonating. Straight pipe exhaust, no muffler, no timing retard, no intercooler etc. Second engine stock long block, lasted for a little bit, had an intercooler, still no timing retard devise, loud muffler less exhaust. He has more details about his adventures on turbocharging.
I would say, 15 - 20 psi, (guestimation) control detonation, run methanol injection & the best pump gas you can put in it.
I'd say, throw on the turbo, just run low boost & avoid detonation.
I'm on the fence about if I'll leave the stock pistons in the engine or not. I likely have a set of L2289+.030" pistons coming my way for next to nothing, but if I use them, it'll be a complete engine tear down again and likely get some valve relief's cut into them for insurance. Or, I can try for up to 15 psi of boost, with intercooler and plenty of data logging.
Fortunately for inline engines, when changing pistons, if all the pistons weight the same it is essentially self balanced.
Well sirs, I intend on a pretty serious street car. I'd love track time also. So, I'm thinking forged pistons, proper cam, I have a 292 exhaust manifold, offy intake. There will be a j & s unit. Meth injection, also.
Question: if I build a box for the carb, what kind of boost can the carb take? I know the fuel pressure needs to be 4-7 psi above maximum boost. The floats need to be filled. Choke horn removed. Anything else?
I have no concerns with doing a draw through at 20 psi boost. It's just not optimal.
A boxed in carb should be able to take any pressure you can throw at it. Don't they make the neoprenen (solid rubber ones) for those carbs? Just reference the fuel pressure according to the pressure in the box.
I seem to bet terrible at finding parts... does anyone know off hand where to get solid floats? I just looked at summit racing and didn't come up with them. I have a Holley 500 2 barrel.
Yes nitrophyl, Jegs has them. Is your carb a center hung float or side. Don't use a box way too much trouble, just blow through, change floats, reference fuel pump and power valve to intake manifold your done.
What do you mean, power valve to the intake? I'm not sure about the floats... I have taken the top off the carb to check.
So, if blow through is that simple... then I have a new dilemma! I have $1300 to spend on this turbo system right now. I have the turbo, card, intake and exhaust. Nothing else. Do I intercooler or meth inject? OR do I buy the j& s? I can only afford one at this time, as I still need to buy the wastegate, BOV, do the exhaust, etc.
Do not intercool or any other tricks , just get a wastegate you need it.
To make it real simple Just block off the power valve with a power valve plug and increase the jets to make it the same area (jet area and power valve restrictor area) If you don't know how to do this just post the jet size and the size of the two small holes under the power valve and I will post the proper jet size to use.
Then all you have to spend $ on is to fab the exhaust and a hat for the carb.
You still need to reference the fuel pump on any turbo setup so the pump sees the boost psi to keep the fuel pressure correct, this is only running a line from the intake manifold to the atmosphere side of the fuel pump diaphragm ( vent )
If you keep the boost low run good gas & conservative timing.
You should not need & J&S or intercooler right away.
Problem is, once you start making boost it gets addicting & you'll want to run more & more boost, & you will not have the good & safer supporting mods to your turbo set-up.
You'll just need to have self control, it's hard, though, ask Snowman.
Curious, what turbo do you have, what are the specs? MBHD
I'm on the fence about if I'll leave the stock pistons in the engine or not. I likely have a set of L2289+.030" pistons coming my way for next to nothing,
Fortunately for inline engines, when changing pistons, if all the pistons weight the same it is essentially self balanced.
What is the angle of the valves?
Our 194-292 engines, the valves are at a shallow angle less than 24*
When we use SBC pistons, the valve reliefs are in the wrong spot, & we really do not need any reliefs & can run flat tops (w/no valve reliefs) up to a certain lift & duration camshaft. There is a mile of clearance, wondering if the Poncho 6 has a lot of room also?
Could I remove the mechanical weights from the distributor and drill a hole in them, thus reducing the amount of advance that they provide? Or would stinger springs be the better way?
If I'm going blow through, I'm going to run an intercooler as a minimum. My thoughts on the draw through is that the charge would reduce the temperature of the intake. Is that logic sound?
I would just weld/braze the advance slot so there is less travel, in a pinch I have used a piece of rubber hose & put it in the one side of the slot.
Stiffer springs, maybe, if you are detonating & need to limit the advance, but, I would not go that way.
Wise choice on the intercooler, they are very affordable including the piping.
On a draw through, the gas does some sort of cooling, but not like an intercooler. It's still going to make the intake manifold hot, pressurized air is pretty hot.
If the blow through is as easy as turbo-6 is sayin, I'm going that route. I will definitely run an intercooler! I need to re-read about cooler design and which is best.
Admittedly, I'm an idiot and I will make mistakes with my build! I am only going to push 7 psi on the current engine. Once the new engine is built (to handle the turbo), then I will go up to 20 psi. That said, anything I can do to make my engine survive while saving/building the new engine will be done to the best of my budget/ability!
I'm ready to move on this and make it happen! I finally have my tig welder! Stoked!
I can't give specs on my turbo because I don't know them 60 a/r is on the housing. I don't k own what to measure or check to know anything else on it.
This turbo came from a mk3 supra with the 3L inline 6. Was running 20lbs. It had a few hours of dyno time and one street race. He got caught and fined $10,000. Tried fighting it and lost. He was liquidating and I scored.
Got the float. Ordered the power valve block off.... the speed shop ordered the wrong thing. It came I as the check valve with drill bit. Picked up my 38mm wastegate today. It came with 7, 11 & 15 psi springs. It will remain at 7 on this engine!!!!
Picked up my bov last night! Fuel pump is in at NAPA. Need to boost reference it. Power valve plug will be in tomorrow. Need to find some mandrel bends locally and I'm off to the races.
Found some tube last night at a local exhaust shop! Ordered a 292 exhaust manifold.... should see it end of next week! That pushes my deadline pretty tight! If I get as much done as I can in prep for the manifold, should do ok for time.
Picked up my bov last night! Fuel pump is in at NAPA. Need to boost reference it. Power valve plug will be in tomorrow. Need to find some mandrel bends locally and I'm off to the races.
Need to post some pics if you can.
MBHD
I thought you said you have a 292 exhaust manifold? Post #84863
Sadly, what I thought was a 292 exhaust manifold only has a 2" outlet. Though it does look right. I haven't had much luck posting pictures, but I will see what I can do!
God doesn't like ugly.
