VI Cutty

How did you decide your HP and Torque goals on your rebuild...what factors did you consider and how did they impact your choices?

I've come up with 450 hp/525 torque through no scientific or well informed process at this point. I chose 450 hp looking to improve power without going so far that I start braking parts down the driveline and 525 torque because...well, no defensible reason. Am I out to lunch?

The car (1970 Cutlass S) will be a street car, rarely if ever on the track. Highway speeds between 60 and 80 mph (with occasional gusts of course). The plan is a Tremec TKX 5 speed transmission and a limited slip rear end with a goal of "spirited" driving with a nice edge over stock builds.

What kind of numbers would you aim for if this was your build (but not rich lol)?

coppercutlass

Unless you plan on racing dont worry about the HP. People love to brag the HP Dyno numbers but unless you plan on translating that into a time slip just enjoy it. Keep in mind the HP will be made well out of the driving RPM range. My 72 cutlass which is completely cool on the street with 3.90's and a 4500 stall runs 11.60's making about 420 ish HP with a 350 . Cruises above 4k rpm where the engine isn't even busting a sweat but it's spun to 7k rpm. My car was built with a very limited budget over the years . Just build a well planned engine for it's use . As soon as you tell the engine builder you have a "goal " he will sell you stuff you don't need.

​​​​​with my particular set up first time out it ran 12.00 and over the course of a season we chopped it down to 11.80's and then eventually 11.60's just maximizing the combo around the engine . So once the car ran i made no changes to the engine.

Fun71

I had no plans for a HP or TQ target during the rebuild of my 350 engine. I researched camshafts ad nauseum to determine a profile that would work well with my intended usage of a daily driver / hot rod / spirited driving.

As to your question of how much is enough, it is never enough as you always want more.

fleming442

Don't you have an LS? You can run 700-1000hp and stay very street friendly. It depends on how deep your pockets are.

I don't know what my 468 Olds does. It's built for longevity and to run on pump gas. Car and driver are 3775lbs, and it went 12.07@117. The Wallace calculation was 420rwhp, I think. There are mid to low 11s in the mph. I just need to learn how to drive. The EFI seems to be running better, so maybe more power was unlocked? Find out in the spring.

Lonnies Performance

It all depends on your needs, but 450HP will put you in modern performance car territory as well as at the epitome of 70's performance.
Your 525 ft/lb is not out of line if building a big block.

Keep the drivability & fuel requirements in mind. It takes the fun out of cruising when you get single digit mileage on $9 per gal. race fuel.
Unless you are a drag racer at heart, you will ultimately have more fun with a pump gas build that you can drive for long distances.

You are on target with a TKX trans.
I just put one in my 68 Camaro... it was the best thing I ever did.
Now I can cruise on the highway with 4.10's & not run at 4000rpm in the slow lane.
The close ratio version with 3.73's is a nice combination.

olds 307 and 403

A modern 5 spd with a decent gear ratio needs much less HP/TQ to be fun. There will always be something faster, plenty of cars run 12's or faster factory. I figure the maybe 400 HP/TQ, after weighing options with Cutlassefi was enough for me. Add in better ratios 4 spd OD with a 3.08 posi will be a very comfortable 70+ mph cruiser for hours on end. It should keep up or beat the base modern muscle cars and get 20+ Imperial MPG highway. As long as it handily beats my Winter driver 305 HP/8spd auto 3.09 differentials AWD 2017 Dodge Challenger GT in a straight line, I will be happy. It will still fall about 15 mpg short unfortunately but isn't the main reason we own them.

VI Cutty

I don't have a dragstrip nearby anymore unfortunately, so this will just be a street car. When I ask for suggestions on engine components the first thing people seem to want to know are my hp/torque goals. Bit of a catch 22 :-D Throwing together a list of engine components without having a target zone established also doesn't make sense (to me at least)...So I feel that if I can establish at least a target zone, I will hopefully have something close to an educated guess as to how much engine I'm building without winding up with more than I want. My engine builder has done plenty of Olds but many more other makes so I want/need to have a pretty good idea of what I want.

I might always want more, but not at the expense of having to replace unplanned breakage because I wound up with too much more :-D

No LS here, sticking with Olds in the bay. Cost of doing an LS would be about the same as building a 455 anyhow...and 700 hp is way more than I want. I'll be running carburation, at least for the first while. We have 94 octane ethanol free gas here which is all I would be running anyhow.

None of this is about "needs" :-D I just don't want to be the slowest and I know I'll never be the fastest with the crowd I run with. I enjoy racing but haven't done it for years. The nearest dragstrip isn't very practical to get to unfortunately. We have 94 octane ethanol free pump gas here which is all I run in my old cars and small engines.

Good to know about the 3.73's...still trying to figure out which one I need. Just learned the rear end I've been planning to use has 2.78's in it...have to check my other spare next. Might have to budget for new gears there too.

pettrix

If you are doing a 455 from scratch (besides having a shortblock). You are looking at around $8k + to get a reliable 455 that will get into that power range.

Aluminum Heads - $2k (Edelbrocks are not available "yet")
Eagle/Scat Rods - $500
Cam, Pushrods, Rockers, Lifters - $1,500
Aluminum Lightweight Piston - $800
Aluminum Intake - $500
Machine Shop Work - $2k
Gaskets, 7 qt pan, Headers, etc - $1k

500HP is easily achievable with some minor head work and a good cam.

The 2.78 gear will make even a 500HP engine seem like a turd on the street. In addition, the numerically lower number will actually put more stress on the engine when accelerating from a stop. Get something in the 3.50 - 4.10 range, especially with an overdrive trans. The new C8 Corvette has a 5.11 gear ratio and can run 11.30's in the 1/4 mile with 490 HP. With some minor tuning, it can run high 10's. Gear ratios are vital to performance.

VI Cutty

That's about the budget I'm looking at, with some wiggle room as required. Being in Canada adds a few bucks as well, unfortunately. Aluminum heads aren't really in the budget, but I have a pair of C heads that were worked over by a knowledgeable fellow so hopefully they help a bit.

That was the impression I got when checking RPMs at various speeds. I have to check my other rear end first but will probably be shopping for new rear end gears too.

pettrix

Not sure what pump gas they sell in Canada but you will have to keep the compression ratio at or below 10.0:1 with iron heads or you run the risk of detonation. 91 or better octane will be needed with iron heads. With aluminum heads you can go 11:5.1 with pump gas

VI Cutty

94 Octane ethanol free readily available locally. Aiming for 10.0:1 already

fleming442

So, from what I've learned, your power is limited to head flow. Pick your heads, then build around them.

BillK

I think with the Tremec and a 3.73 or so gear you will be able to fry the tires with almost any amount of power I personally think a true 400 horsepower is more than most people realize. 450 hp and torque is more than 99% of people need.

matt69olds

There is definitely some truth to this. People spend way too much time watching YouTube and the tv shows, they have no clue what a 12 second car feels like.

I can’t tell you the number of times I have been at the dragstrip and den the look of huge disappointment on owners faces wheb their “fast easy 11 second” car barely runs in the 13s.

fleming442

Hey! I'm right here, dammit!

olds 307 and 403

Do you have another rear end or are you building the 8.5" Type O? You can only get 3.42 or 3.90 gears for it, aftermarket. You are looking at $1500 Canadian easy just for parts by the time you pay shipping. The 70 has the better factory lubed, bolt in axles but a manual is much harder on parts, Moser axles are a good investment. I just picked up used 3.08 Type O gears, saved about $300 on the gears over new. You are lucky to have readily available 94, only 91 non ethanol in most of Saskatchewan. You probably want the 3.90 gears, depending on your cam choice, which probably won't like under 2000 rpm highway cruising speeds. Of course it depends on your highway speed limits, 110 km/hr is the fastest here with about 10ish km/hr leeway here if Cops are around. Better modern pistons and afterarket rods are a no brainer on the heavy bottom end parts 455 with a manual transmission. Good luck sounds like a great build and will be a fun car.

OLDSter Ralph

I look at it as a chosen power level that is desired by the car owner. It can be based on what friends say they have or a number out of the air. It gives the engine builder an idea what parts are needed to accomplish that power level.
Think of it as ordering a steak at a restaurant. You specify rare, medium or well done.

bccan

In my experience, on the street, once you go over 450 ft/lbs with any gear above 3.23 in these cars, one tends to see a lot of white smoke from the tires and/or drive at approximately 15-30 degree yaw under heavy throttle acceleration unless steps are taken, which often leads to less streetability. Of course everyone has a different definition of “street manners.”

I find that around town in suburban CT, with traffic, my car rarely sees the high side of 2000 rpm. Point being, build for torque, that’s what makes a car fun on the street and efficient for cruising and spirited driving. Overdrive trannies are a nice way to have your cake and it too - gear low for acceleration with the benefit of low engine speed on open highways and interstates.

I applaud your stated power goal, I wonder if it could be that it’s right where my engine lands?!? I have constantly thought about thinner head gaskets, a bigger cam, some port work and the corresponding carb recalibration for an appreciable power boost but then I stop and ask why. How often will I use it where those power gains are found? What does that do to the torque curve? What does it do to casual driving efficiency and throttle response? Though gas mileage is a distant concern, the car gets really decent mpg because it’s efficient in the range that it is most used for - casual driving. Even a track day consisting of a 200+ mile round trip over varying roads, a bunch of low 12 second passes and arriving home with a quarter tank of fuel, how bad is that?

2 cents offered.

​​​​​​….

Andy

Budget determines your goals as well as anything, the higher horsepower the more has to go into the drive train. However with no desire for track time build it to have fun with and not be a pain in the *** to drive.. you can have a **** ton of fun with 400-425 horsepower and not break the bank. Personally I look more at matching the components than what horse/ torque will be, they will be what they will be .. design compression under 10:1 for pump gas, cam , you going roller or hydraulic? You can call the cam companies, they will need gears, tire size ,driving goals etc and they will give you a few options.. a 455, decent mid range cam, aluminum heads, solid tune with that trx should be very adequate and put many smiles onyour face that cannot be wiped off easily..lol. Enjoy

fleming442

You can go higher than 10:1 on pump gas

VI Cutty

Lots of great input, thanks!

All part of the motivation behind the question! I have friends running 550 to 800 hp or more in their street cars and apart from the obvious expense to get there, they seem to have way more power than they can actually use practically or safely on the street. Sure, it's impressive but I know that's not the level I want to be at.

I have 2 to pick from. One's in a 1970 Cutlass (the disappointing 2.78) which I'm assuming is a type O (still trying to find the stamp) and the other is under a stack of parts in the yard. I have to drag that one out and figure out what it is...it came in another '70 but I don't know if it was original to that car as the engine/trans weren't original.

I haven't got to the cam just yet, trying to figure out all these pieces of the puzzle so I all the components can be selected to work well as a whole. Unusually holistic of me, really. Most limits around here are 90 - 100 km/h with some 110 km/hr stretches further north. We get about 20 km leeway but still have to be careful.

Thanks, I'm looking forward to driving it! The 94 is great to have but I'm hedging my bets that it will eventually fade away in favour of 91 or 92. Only Chevron carries the 94 but the pumps are busy with all the street cars on cruise nights!

H Beams are in the plan, still looking at pistons but planning to avoid the L2323F's if I can.

Good info, thanks. I'd like to keep emissions of white smoke at my discretion and avoid Mustang syndrome :-D

Absolutely. I had the use of a 67 Parisienne convertible for a while...454 with a 4 speed. I don't know what gears or was in the engine, but the torque made for great driving in town.

And appreciated! Hopefully I can get close enough to the right combination that I won't feel the need to revisit it after everything is together!

Ultimately I think I'll be happy anywhere in between 400-450 hp. Definitely watching the additional costs associate with the rear end needs and so forth. I don't want any more than 10.0:1 compression - iron heads with 94 octane but hedging my bets that the 94 won't be available "forever".

I'll be using a Hydraulic cam and likely roller rockers. As mentioned, I still have some homework to do on my rear end options so those choices can inform the other decisions.

What sort of things can contribute to optimizing the torque produced at useable RPMs?

fleming442

I suffer from OCD. Overkill Compulsive Disorder is real folks. Too much is just right until it's not enough, again. And, again. And, again.

coppercutlass

Picking a cam and certain component should come down to use and vehicle specifics. It's more simpler than one would think. With every engine I have built in have taken it up a hair. Where most guys would want quantum leaps. I bump up the compression a bit and pick the cam accordingly to the current combo and compression. Once it runs I make endless small changes to squeeze as much power as possible which can still be done even without track time now thanks to devices like the draggy . The most fun engine I had in the car was probably the 370 HP combo when the car was all steel. It ran 12.2's would shred tires was realistic at 3500 lbs had power breaks and I would drive it to the track and back and daily drive it. Currently although it's just as capable on the street it's become a potato chip at 3285 lbs with me in it and just unsafe for the road for my safety as I took alot of metal out when I repainted it . My Pontiac is a tame bunny compared to my olds and it can barely spin the tires but I enjoy just driving it and it had just enough power to keep up with modern cars. It might make 300 HP. Perhaps it's the discipline from all the years in the track but on the street I drive like an old man. I have never done a big burnout on the street. I think I can count the amount of times I did a rolling burnout on my two hands over the last 20 years. Moral of the story a well picked out engine combo to it's use and car set up will deliver what you want effortlessly with a 455 even with a towing cam and 9 to 1 compression. You are driving on the lower RPM where as the HP will usually be made well above driving RPM.

NTXOlds

I would say that I am in the same boat as the OP. Since I have a 68 Cutlass convertible, I have no plans to ever run it at the track, but I want it to be fun and responsive.

My thought is to maximize two things: torque and efficiency. Whatever the HP ends up is whatever it will have. Since I will be starting with a 350 SBO, when the time is right I intend to contact @cutlassefi to build it into a stroker motor. The extra stroke will help with the torque, and the lighter reciprocating weight of the modern internals will also help with efficiency. For my goals, there is no NEED for the new Edelbrock SBO aluminum heads, but I want them anyway. The better the engine can breathe at all RPMs, the more efficient it can be. I want to run pump gas, so I would aim for 9.5 or 10 to 1 compression, and I intend to run multiport EFI with timing control. I will work with Mark to pick out a cam that will still have plenty of vacuum and a good idle.

I know that I could pick up almost any 455, drop it in and have a ton of fun, too, but I really like the idea of creating a fun and efficient SBO with the original engine.

Now I also have dreams of building a street / strip sleeper with a 65-67 Cutlass and a boosted 425, but that will have to wait until I have more time and money.