View Full Version : Help me get just the right parts.

08-25-2005, 09:24 PM
I am going to build a motor for an ATI D-1SC. This motor will be used 95% of the time on the street. My HP goal is about 650, I want to run 8-10 psi. The motor will be a SBC 350 with 3 Ĺ stroke and 4 1/8 or so bore.
I was looking at getting an Eagle 4340 crank and H beam rods. One question is do I need a special cam or will a off the shelf blower cam work just fine. I know that I donít need the best heads since I will be using a blower but I guess I am asking for a range or an idea where I should be at. I donít plan on going over 8.5:1 compression. The motor will also be fuel injected. No I wonít be doing the tuning.

08-26-2005, 01:49 AM
I think you should go right to ATI and get their recommendation. Best advice you can get is right from the horses mouth...

Rick Dorion
08-26-2005, 03:47 AM
I don't know about that bore size you want on a 350 block.

08-26-2005, 10:08 AM
It just seems that everyone thinks that ATI's help is not worth a darn.

08-26-2005, 07:02 PM
ATI has mixed answers..

First.. Stay around 9.0-1 compression.. lower than that kills overall HP and TQ numbers! and over 9.5 compression, and you are taking chances of detonation without an intercooler.. expecially when you dont for sure know the quality of the gas you are running..

2nd.. Use aluminum heads.. AFR, Dart pro 1s, or really anything that flows well and aluminum.. dont go crazy on huge intake ports (over 215) because they hurt lowend driveablility! AFRs with 190-195s work awsome... Dart pro 1s with CNC ports are also very nice..

To make the best horsepower you will need to try to match the cam to your heads!... a cam with a split pattern will work best.. 234/244 duration 480/495 lift.. 112 centerline.. You could go smaller on the cam but you would have to use more boost in order to get the 650 hp you want..

It is suggested you use an intercooler..

It is suggested that you use a boost timing controler...(too much timing at the wrong time can cause detonation and blow up the engine)

You could easily build a normal 355 (NONE STROKER) with H beam rods, forged crank and aluminum heads and run 10-12 PSI of boost with an intercooler and make well over 700hp. it all depends on the setup..

If you have any further questions feel free to email me.. I just finished my engine and have delt alot with ATI and found them to be not much help. and have had to learn from my mistakes..

You can find more info from my setup from the VBGARAGE under PROJECT-N-SANE


08-26-2005, 07:15 PM
if you are building a 350 engine.. you will want to stay with as small of bore size as possible (larger the bore the weaker the engine walls)

You dont need exotic bore/stroke/ and crank combos to make 650hp with a blower..

08-27-2005, 07:00 AM
I am using a Comp cams xe hyd roller in my 383 that idles around 850 rpm, is smooth and makes about 14-15" of vac. This is a blower cam that the lt1 guys use with great success. The specs are 224/236 @ .050, .573/.593 lift w/ 1.5 rockers and I'm using 116 lsa. You could cut the lsa down to 114. This cam has made your hp goals many times over!
In my opinion, if you are building a motor with all new stuff go with a 383 for the same cost.With a 383 you can use bigger heads and still have good driveability. If you use Eagle (or any offshore) products make sure you check the specs as they have been known to be out. If you go with 8-8.5 comp. you will be a little safer as far as detonation is concerned.Low comp and high boost makes more power than high comp and low boost!
My specs: 383, 3.75 stroke Eagle 4340 crank, 6" Eagle 4340 rods, Srp -16cc forged pistons in a (factory roller cam) 1pc seal ,4 bolt block. I use cometic head gaskets and TFS 195 23* heads w/ 72cc chambers. The cam mentioned earlier, TPIS miniram intake, 55lb injectors and Electromotive Tec 2 ecu. Procharger D1sc, 10 lbs boost (for now) and no intercooler (yet).
My buddy is tuning my car now but it should make power close to your goals (I hope).

08-27-2005, 11:22 AM
Don't bother callling ATI. Their tech support department is worthless.

My general recommendations, since I also have a procharged and injected 350 in the approximately 650rwhp level (no dyno numbers yet, but it uses 490 pph of fuel at WOT and slowly pulls away from a friend's bike that traps 127-128 mph at 3840 lbs, so it's not hard to run the numbers.)

The Eagle crank and rods will be fine, but check them over thoroughly. If you can spend a bit more, buy domestic. Scat's 4340 stuff, while forged offshore, is finish machined and quality inspected here in the US, and I would prefer them to Eagle. Use quality (i.e. ARP) fasteners everywhere.

If you're starting from fresh and want to do things *really* right, consider modding the block with piston squirters; the comparatively cool oil constantly showering the underside of the piston will help keep the piston temps down and therefore provide some additional detonation resistance. CV Products sells a kit for this. This has been an OEM trick for many many years on forced induction engines. You can also go one step further and use EDM'd rods for pressurized wrist pin oiling.

Head gaskets: Use MLS gaskets if your machine shop can provide a good enough block and head surface finish for them (32 RA or less, <.002" / inch flatness.) MLS gaskets (Cometic, Fel-Pro's new ones, etc.) are the only way to fly but only if you can provide smooth enough surfaces for them, otherwise they leak.

Pistons: shoot for around 9.0-9.25:1 compression. That's the "sweet spot" for centrifugal engines, offering a great mix of off-boost efficiency and still allowing enough boost to make plenty of power. Too low on the compression and the engine will be over-cammed/under compressed and combustion temps will be too low, leading to poor mileage and fouled plugs. Even at 9.0-9.25:1 with a proper cam it will be over cammed/undercompressed when not "on boost" but you can make up for that with plenty of timing in the cruise areas. It's in your best interest to ceramic coat the piston domes and also the chambers and valve faces in the heads, it will help prevent detonation.

Heads: Unfortunately you are dead wrong on your thoughts of "not needing the best heads." On the other hand, you want EXCELLENT heads. You want flow. Lots of flow, especially on the exhaust side but don't skimp on the intake side either. Get the best flowing heads you can afford. Remember to size the valvesprings so they still have adequate closing pressure with the boost pressure on the intake runner side trying to hold them open. Inconel exhaust valves, while not a must, wouldn't be a bad idea. Remember, even though the blower is shoving air into the engine you need to get all the additional combustion gasses out (i.e. you want very good exhaust port flow.) And on the intake side, the better they flow means you can make more power with less boost-- this means not spinning the supercharger as fast, which means less power to drive the supercharger and a cooler intake charge meaning less chances of detonation.

Cam: what are you going, flat tappet or roller? You'll want a specific blower grind to keep the boost in the cylinder, typically 112-114 LSA. You'll probably want something in the 23X-24X @ .050 range at that power level and lift probably in the .520 / .560 range, but that's more dependant on what your head/spring combo allows and your port flow specs. More exhaust lift/duration is a must to get all the exhaust out. For instance, my cam is a custom grind HR, 242/254 @ .050, lift .540/.585 with 1.5 rockers, 114 LSA. This cam was intended to work with my combo and head flow numbers. Going wider on the LSA, up to a point, will provide better idle and more vacuum. Unfortunately a really wide LSA also contributes to sky-high EGT's. I wouldn't go much wider than 114 LSA. A tighter LSA won't build as much boost and will bleed off a bit of low-end but will help lower EGT's. My preference is 112-114 LSA.

When you go to buy injectors, buy conservative and buy larger than you think you will need. I started off with 55 lb/hr injectors figuring they would be adequate and they were maxed at only 5300 rpm after I got my car back on the road. I stepped up to 75 lb/hr injectors and now have a bit of headroom to be on the safe side (usually a max 82% duty cycle at WOT at the torque peak about 5500 rpm)

You didn't mention what kind of EFI intake you would be using. If you're going to use a converted "single plane" style with a 4-barrel throttle body up top that will require the use of a carb hat, be warned that most of the carb hats out there provide very poor and uneven airflow which can throw off the mixture cylinder to cylinder. The only good hats "out of the box" out there are the CSU, Extreme Velocity, and SDCE hat.

An excellent resource and and all-around nice guy who really knows centrifugal motors is Scott at SD Concept Engineering (http://www.sd-concepts.com/); he helped plan my motor and came up with my camshaft for me. He also does spring tensioner retrofits on the ATI brackets which greatly increase belt life and eliminate slip. His number is 401-826-4400. Good prices on stuff too. Just be warned, it's a one-man show at his place and he can be difficult to get in touch with. He's a wealth of information once you do though.


08-27-2005, 10:21 PM
Hey thanks for the great replys, I hope to figure how my motor will turn out so I can get in on the group purchase from frank on the pro-charger.

I can most likely spend a little more and get a domestic crank and rods. I will be using all ARP fasteners.
I love the idea of using oil squirters, I have seen them used on diesel motors and on some all out race motors.
I will be using a hydraulic roller cam. I will be using Electromotiveís TEC3 EFI system, and will most likely use a sheet metal intake with a single throttle body built into the front of the intake.
Scott at SD Concept Engineering does come recommended by others as well. I bet its even harder to get in touch with him now that he was mentioned in Car Craft.

08-28-2005, 01:52 PM
Scott at SD Concept Engineering does come recommended by others as well. I bet its even harder to get in touch with him now that he was mentioned in Car Craft.

Scott has had LOT of problems this year-- right about the first of the year the complex his old building was in was bought out by someone else who tripled his lease after a couple months; he had to go out, buy a new building, and move all his stuff during winter in Rhode Island... a difficult task, especially when you're a small shop. On top of that, his phone number changed and for a while there wasn't an answering machine at either number. He was constantly running back and forth moving stuff from the old shop to the new shop and you couldn't get a hold of him on either land line-- which in my case was very worrying since I was waiting for parts I had paid for. To top it off, soon after the move one of his close friends and shop helpers comitted suicide. Not a good year for him, that's for sure.

Another thing to keep in mind about Scott is he does NOT beat around the bush or mince words. Some people take his mannerisms and words as personal attacks, but that's not the case; he's just plainly speaking his mind without sugar-coating the advice. Some people can't deal with that. If you have junky parts or have pieced together a combo that has problems, he'll tell you flat out that you screwed up, so I can see where some people would take that personally. On the other hand, I found his brutally honest approach extremely refreshing and could (and did) spend hours on the phone with the guy. Very, very knowledgeable.

Good luck with the build... I think you'll be happy. Also, not to knock Frank's group buy, but if you might want to give Scott a ring and check his pricing, especially if you want the blower bracket retrofitted with a spring tensioner; he can order you the Procharger, do the bracket mods and ship it to you ready to go. Personally, I wouldn't run an ATI bracket without Scott's spring tensioner retrofit. I have 8,000+ miles on my *original* 8-rib belt now at 15 psi of boost, and it doesn't slip one bit. I spin the car up to redline quite often. With the standard ATI tensioner it's hard to get the belts not to slip at higher boost levels, and you've typically got to crank the tension so high you eat up the front blower bearing.

Also, since you're going with an HR let me offer two pieces of advice on HR's:
1. Pay a few extra bucks and have it ground on a billet core with a pressed-on iron distributor gear.
2. Use a GM melonized distributor gear. DO NOT USE AN MSD GEAR!

In the last 5 years I have had two failures with cast core hydraulic rollers with MSD's "melonized" gears; the first cam/gear combo was looking pretty nasty after 7500 miles, and the second combo failed completely-- the gears ate the teeth off each other and trashed all my bearings in 2500 miles. I have heard of and seen many other MSD gears / Comp cast core HR's fail in as little as 26 miles. Running the GM gear fixes all the problems. I have 4,000 miles now on my lastest comp cast core HR with a GM gear and the gears still look brand new.

As far as the billet cam recommendation, that's because I have had several friends this year and have heard reports from several shops who have experienced cast-core HR lobe failures with very low mileage; everyone was running about 150 lbs closed / 360 lbs open, some with rev-kits and some without. The cast core cams just can't seem to take the spring pressures and the lobes start tracking. My engine currently has a cast-core HR cam, so I know I'm tempting fate. I recently had my cam reground on a billet core/iron gear. The new billet grind is sitting in the shop and as soon as I have time I'm pulling the engine to swap it for piece of mind. I'm also going to try a set of the new Beehive valve springs; their self-damping properties and significantly lighter spring and retainer weight is really supposed to help a HR "rev up" better and also redline a bit higher because of the substantial mass savings.


08-28-2005, 07:48 PM
I most likely will end up missing the GP, not that big of a deal. If that does happen I will defiantly give Scott a call.
Some good news is that the Electromotive EFI system is a distributor-less system so I donít have to worry about the distributor gear.
I would like to hear Scottís comments on my motor setup, nothing wrong with constructive criticism.

08-28-2005, 07:57 PM
I most likely will end up missing the GP, not that big of a deal. If that does happen I will defiantly give Scott a call.
Some good news is that the Electromotive EFI system is a distributor-less system so I donít have to worry about the distributor gear.
I would like to hear Scottís comments on my motor setup, nothing wrong with constructive criticism.

You'll still need a distributor gear on a stub shaft to drive the oil pump... unless you're running dry-sump.

08-28-2005, 09:14 PM
I did not even think about that...

08-29-2005, 11:04 AM
You can get a stub shaft / oil pump drive with a hall effect sensor built on top to signal TDC #1 to your ECU, but IIRC the TEC-3 likes to have a trigger wheel on the crank (correct me if I'm wrong.)

08-29-2005, 06:52 PM
I think if you want to run full sequential you will need a crank and cam sensor! I have a Tec 2 system that just uses a crank trigger for phased sequential control of the ignition/fuel. For an oil pump drive I just took a dist. from a hyd roller cammed Caprice and cut the top off just above the seat/hold down (the part that seats on the intake), then a friend machined it for a small bearing and tapped the top end of the dist. shaft for a hold down bolt.The setup works great for me.

08-29-2005, 09:25 PM
Blown69nova: you probably have a better idea then I do. We use a TEC3 system in our Bonneville car, currently we only use it for ignition timing. Itís a mechanical injection Nitro motor. We want to some day to convert it to EFI. We have a spare ECU so that is why I am going to use it, since it is ďkindaĒ free. I know we use the crank trigger currently but I donít know anything about a cam trigger. We have a lot to figure out.

08-30-2005, 02:28 PM
If i get the bracket from SD then do i need to get a water pump that is reversed? Does anyone know of a kit that will allow the use of one belt for all the goodies, A/C, P/S, etc... So far i think that this is the best post about this setup. https://www.pro-touring.com/forum/showthread.php?t=971